Sizing Blinged LC 7.62 Brass in a Summit and a RockChucker II.

[GWS]

Using an RCBS .308 small base sizer on some once-shot LC brass, I came across an interesting behavior. Sizing the properly lubed brass once gave me anywhere from .001" to .007" runout as measured by the RCBS Casemaster 1/8" from the mouth of each case. (measurement is post sized brass only no bullets involved sized on both a Summit and a Rock Chucker II.)

That was surprising me so then I rotated the brass a third and sized again. Measured Runout was reduced in every case, excepting those that measured .001 the first time, stayed there. I rotated the brass again another third and resized a third time. Runout on most cases now wavered between .001 and .002?????????

You'd think that if a sizer/press combo was going to create runout it would continue to create runout no matter how many times through the sizer. Then I realized that the run-out may have been caused by uneven spring-back of the brass and perhaps multiple sizing reduces the spring-back. (if that's the case rotating the brass was needless.) BTW, yes the LC brass had somerunout before sizing but it ran .001 to .004.

Am I nuts, or is this something you pros have run in to as well?

Let me preface the above by explaining what I'm up to. I have a new RCBS Summit Press, and my venerable Rock Chucker II, and I'm attempting to compare the two presses with the following (I think) worthy test:

1. Size LC 7.62 brass recently tumbled (blinged) using a Thumlers & S.S. media on both presses using the same RCBS Small Base Sizer. Expecting blinged brass to be hard to size, I want to compare effort in sizing as well, while doing my best to not stretch and/or warp the necks with the expander ball.

2. Measure each with an RCBS Casemaster for runout. (once I find the best way to lube and size).

3. After careful case prep, I plan to prime & charge the cases and then seat them with a new RCBS Gold Medal Seater. (whoa....a third test!) Always wanted to know if the G.M.S could do as good a job as Redding's or Forster's, because if so, dropping bullets in from the top is way faster than placing bullets and leading them into the die as you stroke.....would prevent accidental smashed fingers too if you get a little too speedy.

4. Finally will remeasure finished rounds for runout. Will take the best 10 from each press and shoot them in my Remington R25.....known to shoot subMOA @100 Meters even with 165g Factory Remington Corelokts, but I want to see what Nosler 165g Ballistic-Tip bullets over IMR4895 will do. (CCI LR primers)

I offered up first problem in the thread "Hornady Concentricity Gauge", and was answered by Bart B. & Uncle Nick. Here's their replies:

From Bart B.: If your sizing die's a bit on the bit size in neck diameter, your sized case necks may not bend much as the expander ball comes up through them after they're sized down. That happens.

If you get .002" runout on necks, bullet runout may be .004" to .005", so lets see what bullet runout is on loaded rounds.

From Uncle Nick: GWS, the case pressed into the die should be as straight as the die. We've already noted that reducing drag of the expander reduces it's tendency to pull the neck off axis, so I'm wondering if the repeated sizing isn't mainly burnishing inside the neck and reducing expander friction that way. That would suggest getting the case necks really clean and well-lubed inside might have the same result. Multiple sizing has the problem that it adds work hardening and increases the frequency with which you'll need to anneal to avoid splits, so it would be worth establishing what's going on. Let us know how not-rotating does for you?

Well it became obvious I needed to do my own thread on this and stop the highjack. So here it is:

 

[GWS]

My blinged once shot LC 2013 7.62 brass! The first Whoa with my project came when I couldn't resize it at all with either press!....Even using both hands on the press handles! (and this wasn't my first trip around LC brass)

I was using Imperial Wax like I always do, but the friction was just too great....I almost stuck a case.

So I added a little more Imperial......even used a q-tip inside the neck ....and it was worse!!! Wow I had no idea too much bling would do that.

Next step was to clean the die of Imperial. No, there was no wax buildup before My sizing attempts....the die was just cleaned before this project started. I decided to get out my RCBS Lube Pad and try that. (Using the bristle brush inside the necks) That was more like it.....a little firm but not like almost separating the base from the rest of the brass. I've used Imperial for years and never had that happen.

So using this method and experimenting with the lubing method inside the neck, I found I got the least friction, pulling the expander out, by dipping the necks in dry Mica after the lube brush. Surprise #3! Anyway, that's the method I was using when I tested Runout on the brass. Didn't bother with the couple I barely managed to pull out of the die using Imperial. Next week I will try lanolin spray lube to see if that betters the Lube pad/Mica method. I'll be back.
(Uncle Nick, before I try the new lube, I will try sizing twice then three times without turning the cases...so we know.)

 

[GWS]

Saturday: The First Test Using the Rock Chucker

Lube was ample, sizing was easy, no excessive force pulling the expander out. Of course expander pulling got even easier with each successive sizing. All finished brass dropped in my Wilson gauge...heads flush with the lower groove. Trimming necessary...guessing 2 to 4 thousandths.

1. Pre-Sizing Run-out: I measured for run-out 1/8" from the case mouth, 5 cases. Then I marked an index in red on each case head extractor groove.

2. First Sizing: Using an RCBS lube pad and neck brush I lubed each case; oriented each case where the index was centered in the in-slot of the case holder; sized each in the Rock Chucker; then measured each case again for run-out.

3. I sized each case a 2nd time, same orientation, then measured again for run-out.

4. I sized each case a 3rd time, same orientation, measured again for run-out.

5. I sized a 4th time, orientation rotated 1/3 rotation clockwise, measured run-out again.

6. I sized a 5th time, orientation rotated 2/3 rotation clockwise, measured run-out again.

After doing 3 cases this far one actually showed worse run-out after step 6.....so I said what the heck and sized a 6th time, red mark back to index, to see if there was any change.

7. 6th sizing was back at zero (first) orientation.

Ending: All five cases were at a best .001" run-out.

Here's the numbers (run-out in thousandths of an inch):
Sizings: .1.....2.....3.....4.....5.....6
case 1: 2.0--4.0--2.0--2.0--1.5--1.0
case 2: 9.0--6.0--6.0--3.0--2.0--1.0
case 3: 5.0--3.0--2.5--7/8--1.0
case 4: 5.0--3.5--1.5--2.0--2.5--1.0
case 5: 4.0--2.0--1.5--1.25--1.5--1.0

A sixth case I simplified. Presized runout was .004" and first sizing was .005. I immediately rotated the case 1/3, sized, rotated 2/3, sized, and measured once. Run-out was .001"

Strangely nothing ever got better than .001" Well I take that back....case 3, 4th sizing was actually less....maybe 7/8 of a thousandth.

So! What's a progressive reloader to do with this brass! This whole process blindsided me.....sure didn't expect it.

Will see what if anything changes using a lanolin spray lube next week. Here's hoping I don't get a stuck case trying.

 

[higgite]

GWS,

Good info. Thanks for sharing it with us.

While you're testing, would you consider doing a test where you only size each case once, but hold it in the die for a few seconds to see if maybe the brass relaxing while in the die will improve runout? Or has that been documented somewhere already?

BTW, if you said it, I missed it, what sizing die are you using?

 

[GWS]

Sure, you bet! That's certainly worth a try. Thanks for the idea! Your question is answered in the first words of my first post! I do the same thing! Must be a forest through the trees thing! The sizer is (I said it was a worthy test) RCBS's Small-Based Sizer.

 

[higgite]

Your question is answered in the first words of my first post! I do the same thing! Must be a forest through the trees thing!

Oh... THAT first sentence! I hate it when that happens.

 

[Bart B.]

I suggest you check neck runout on a batch of unsized, clean cases; recording and marking each case neck's runout. Next, with the expander ball removed from the sizing die, full length size those cases then measure neck runout on each one. Compare the runout numbers from before to after sizing.

This will show you how straight the case necks are on the case after they're sized down. If they're straighter on average than cases you sized with the expander ball opening up the case mouth a bit, that's proof the expander ball's the culprit for bent case necks.

 

[F. Guffey]

I have never been impressed with Imperial sizing was, other local reloaders/builders/shooters have invested so much time in promoting it are into it so far they can not back out. When one has trouble sizing cases because the case is whipping their presses they have no place to go. When I show up they make one thing clear, we are not going to use a lube that is not on anyone's list of approved lubes to use when sizing cases.

I have never cranked a die down an additional 2 turns (. 142") to increase a presses ability to overcome a cases ability to resist sizing. Until I used Imperial, then Dillon in a can or bottle.

The first Whoa with my project came when I couldn't resize it at all with either press!....Even using both hands on the press handles! (and this wasn't my first trip around LC brass)

LC cases, like Federal primers, If it not for LC brass, I would be low on available brass. If not for Rock Chucker presses I would be missing 4 Rock Chucker presses. I have friends that come over when trouble shooting, we use the Rock Chucker or nothing. That does not change the fact my Rock Chuckers kick the ram forward at the top because the linkage gets tangled up on the bottom. Now that can not be good if it takes the case between the shell holder and die to prevent the ram from kicking forward and I do not care what effect that has on the case when it comes to coming out straight.

I have other presses, the rams go up and the rams go down, that is straight up and straight down without going into a bind. Then there is the

Even using both hands on the press handles!

both hands on the handle. Now that has to be rough on the case, I collapse cases into accordions/bellows when I want to know how if a case needs annealing.

Other local reloaders use Dillon in a can or bottle, I can start with Dillon and or Imperial, but when things get tuff, I get out the good stuff.

F. Guffey

 

[GWS]

I haven't made it back to the reloading room yet...this evening, I hope.

Bart, I did pre-measure, but I did not size without the expander. So if I do and the die makes .000 brass before expanding, then what options are there outside of buying a bushing die....are there better expanders? Hornady or Redding carbide replacements? I've heard there isn't much of an improvement over just turning and polishing what I've got......Oh, btw, I forgot to say that before these operations I polished the expander just a little in a drill press.

Incidentally, does it effect concentricity where the expander is tightened down as long as it is through the neck & free in the case before you pull it out?

F. Guffy said: I have never been impressed with Imperial sizing wax

Well I was....until this experience. I certainly proved that the RCBS lube pad is superior for sizing blinged 7.62 brass! RCBS has stated in their "Faqs" that 90% of their stuck-case removal operations for customers, are cases stuck with "wax products". People guffawed at that accusing RCBS of being proprietorially biased.....but then they can rebrand the wax product like Hornady did, and sell the hell out of it....but they didn't.

Not to worry about the "two hand operation." It lasted for 4 attempts on 4 cases.....and only two to completion (scary it was). Those 2 were scrapped.

I'll pass on the "cam" argument. RCBS presses are all I own, so no point.

I AM waiting for you to tell me what "the good stuff" is, though. I hope not motor oil......that's the messiest oil it the world....it gets everywhere!

You don't like Lanolin either I take it.

 

[Bart B.]

GWS, expanders tend to pull sized down case necks a bit out of alignment as the brass around them at the shoulder is not all exactly the same thickness. Even if you've turned the necks to zero tolerance at some thickness, the shoulder's still a bit uneven in its thickness.

Such is why folks just lapped out the necks of their standard full length sizing dies back in the 60's to a diameter about .002" smaller than that of a loaded round. That was long before bushing dies were made and the accuracy attained by them has yet to be bettered. Sizing fire cases in these only moves the case neck once. Otherwise, the expander ball coming up through it moves it again. Most benchresters have recently moved from neck only sizing to these types of dies. Their case necks end up much straighter on the case shoulder and are better aligned with the case body. They reduce body diameters and set shoulders back on fired cases about .001" and case necks end up with their mouths about .0005" smaller than bullet diameter. You can turn case necks to the right thickness for your die's neck diameter to get the grip on bullets you want. I got a bunch of .308 Win full length dies at a gun show for a few bucks each and lapped their necks out from .332" to .337" for different case neck thickness and bullet diameters.

Even with a case neck wall thickness variance of .001", gelded full length sizing dies with their necks opend up a bit makes for very straight ammo. And any bullet runout on .308/7.62 cases up to .002" is good for half MOA ammo at 600 yards in well built rifles.

Sizing a fired case in you gelded die (no ball) does the same thing and it's neck runout should be minimal. Some 'smiths hone out full length die necks to the customer's dimensions for a nomimal cost.

Bushing dies made by Redding and RCBS are pretty good, but the bushings in them float around and don't hold the case neck in line with the case body when they're sized down. Nor do they size the complete neck but stop short about 1/32nd inch. I don't think they'll size a fired case with its neck as well centered on the case shoulder and in line with the body axis because of that floating bushing. But these dies are probably the best commercially available ones without having a custom die made for your fired cases like some benchresters do.

Regarding sizing lube, there's several good ones on the market. Imperial Sizing Wax is one good one as is plain STP oil treatment. The issue is to get just enough on the case to let it size easy and uniform enough to size each case the same amount. Using any lube wrong results in irregularly sized cases. My favorite since 1969 is a 60/40 percent mix of STP oil treatment and Hoppe's No. 9 bore cleaner. I tumble cleaned cases in a Thumblers Tumbler lined with foam and a few drops of it put on the foam before lubing 50 cases. Excellent case headspace dimensional uniformity doing this.

 

[GWS]

GWS, expanders tend to pull sized down case necks a bit out of alignment as the brass around them at the shoulder is not all exactly the same thickness. Even if you've turned the necks to zero tolerance at some thickness, the shoulder's still a bit uneven in its thickness.

Yes, I'm aware of that and the data I posted shows it. I was surprised that more trips through the sizer almost always got the brass to a pretty respectable .001" runnout. The trick was to get the lube right, inside and out, to quit pulling things out of whack. I am aware that the brass has been over worked in the necks with this process. I see annealing soon in its future. At least I got the brass straight for the test so we can see what the Gold Medal seater can do.

Today I removed the expander as you suggested and the brass stayed put pretty much on....on brass that pre-measured, .002" to .001" and improved more runout to the same .002-.001". It appears the die's best is .001" on either press.

Such is why folks just lapped out the necks of their standard full length sizing dies back in the 60's to a diameter about .002" smaller than that of a loaded round. That was long before bushing dies were made and the accuracy attained by them has yet to be bettered. Sizing fire cases in these only moves the case neck once. Otherwise, the expander ball coming up through it moves it again.

The scope of this press test really doesn't include making benchrest fodder. The idea of lapping has been around for a long time. I just found that for my use in hunting it was a lot of trouble and expense for little gain. Some of us are happy with a little less.

Most benchresters have recently moved from neck only sizing to these types of dies. Their case necks end up much straighter on the case shoulder and are better aligned with the case body. They reduce body diameters and set shoulders back on fired cases about .001" and case necks end up with their mouths about .0005" smaller than bullet diameter. You can turn case necks to the right thickness for your die's neck diameter to get the grip on bullets you want. I got a bunch of .308 Win full length dies at a gun show for a few bucks each and lapped their necks out from .332" to .337" for different case neck thickness and bullet diameters.

Yes, I'm aware benchresters have moved away from neck sizing....interesting it is. Where do you get your dies lapped....or do you have the skills yourself?

Even with a case neck wall thickness variance of .001", gelded full length sizing dies with their necks opened up a bit makes for very straight ammo. And any bullet runout on .308/7.62 cases up to .002" is good for half MOA ammo at 600 yards in well built rifles.

Sizing a fired case in you gelded die (no ball) does the same thing and it's neck runout should be minimal. Some 'smiths hone out full length die necks to the customer's dimensions for a nomimal cost.

I may have to try that one of these days....if I can find someone in these parts who can do that kind of work on hard die steel.

Bushing dies made by Redding and RCBS are pretty good, but the bushings in them float around and don't hold the case neck in line with the case body when they're sized down. Nor do they size the complete neck but stop short about 1/32nd inch. I don't think they'll size a fired case with its neck as well centered on the case shoulder and in line with the body axis because of that floating bushing. But these dies are probably the best commercially available ones without having a custom die made for your fired cases like some benchresters do.

Well, I didn't know that about bushing dies. Would be hard to "fix" such a die. The .001" limitation I found on my RCBS small-base die isn't very much....geeze, 1/3 the thickness of a sticky note. But I guess that counts for benchresters.

Regarding sizing lube, there's several good ones on the market. Imperial Sizing Wax is one good one as is plain STP oil treatment. The issue is to get just enough on the case to let it size easy and uniform enough to size each case the same amount. Using any lube wrong results in irregularly sized cases. My favorite since 1969 is a 60/40 percent mix of STP oil treatment and Hoppe's No. 9 bore cleaner. I tumble cleaned cases in a Thumblers Tumbler lined with foam and a few drops of it put on the foam before lubing 50 cases. Excellent case headspace dimensional uniformity doing this.

Hmmm, maybe STP is what Mr. Guffy likes.....never heard of adding Hoppes to it. Do you add the old formula or the new, or does it make a difference? A few drops on your foam isn't much lube for 50 cases! My wife wouldn't like the Hoppes in the mix......she hates the smell. So maybe my brass just needs another roll in the Thumlers. I may have to try that. I wonder if cutting foam "cubes" and putting them in the brass, would work as well as your foam lining?

BTW, you never use lanolin? I used some of Dillon's spray tonight. It worked, but not as slick as RCBS's lube pad. This brass has been a real test for lubes! Blinged brass really does tax their limits! The only problem with using a lube pad is it's slow, and it's easier to use too much.

The problem with lanolin, IME, is that there is a short window. Miss the window and it looses its slickness. Same with any water-based lube, but at least with the lube pad you lube and size lube and size.....you don't have a bunch a lubed brass drying.

Tonight I duplicated the last session only with the new Summit Press. It worked just as well as the Rock Chucker....no better though. The data so duplicated that with the Rock Chucker I saw no need to bore everybody with it.

I did find three important things out about the Summit press:
1. You have to watch the 4 bolts connecting the casting to the ram (top & bottom).....they work loose, and once loose the press flexes inappropriately when sizing. Must be checked often! (really should be Loc-Tited).
2. It is even more sensitive to mediocre case lube. Yet when lubed well, lever effort is no worse than a Rock Chucker, while visibility and access is a huge improvement!
3. Using the same sizer die as I did in the Rock Chucker, the die has to be screwed in deeper in comparison (more cam-over) than with the Rock Chucker in order to set the shoulder setback far enough to flush case heads at or below "maximum" in my Wilson Gauge! Past what I thought was ample "cam-over".

 

[Bart B.]

With your .001" runout on sized cases from the die without an expander ball, one reason it might be that much instead of .000" is the case body. If your case lays in a V block resting at its shoulder and pressure ring at its back end while its spun, the normal out of round condition of virtually all cases would give that much runout.

Your case runout from being sized in that gelded die may be close enough to zero to call it that. Sized cases from my dies with neck diameters just under loaded round neck diameters have minimal runout. I've put the dial indicator on the case body right behind the shoulder as well as the pressure ring about 1/4" in front of the case head. There's a bit of runout; .001" or less. Few cases have the exact same wall thickness all the way around them.

 

[GWS]

Could you use the Sinclair Expander Die (I realize you are adding a step) in place of the expander ball? Wonder if that tool is an advantage anywhere? It is supposed to be self-centering. (never used one) At least it would prevent work hardening do to the repeated sizing and expanding.

I still don't understand why rotating the case and sizing 3 or 4 times (with expander ball) gets concentricity to .001.....unless its flex in the stem that gets less influential as the sizing does get easier. A stiffer stem and a harder ball may make a lot of difference.

 

[Bart B.]

Any use of an expander ball sizes the neck once after its first time, it's the second sizing operation after the die's neck has sized it down too small. If the die's neck is the right diameter for your cases, the case necks are only sized once.

 

[GWS]

I realize that ideal. But you also have to consider neck wall thickness. The LC brass I'm working with now is going to be thicker than other types of brass like Lapua, federal, etc. That's always the problem. Ideal means you have to have lapped sizers for every brand of brass, pointed out by your statement in a previous post.

I got a bunch of .308 Win full length dies at a gun show for a few bucks each and lapped their necks out from .332" to .337" for different case neck thickness and bullet diameters.

and what does it cost to do that?

Sinclair's new Generation II Expander Dies that feed mandrels used for neck turning may be a good compromise. Wall thickness variation goes outside and leaves you with .002" neck tension. A second sizing yes, but supposedly no neck pulling off-center. And no necessity of repeated sizings like I just experienced.......or so the article says....anyone have experience with those?

Common sense says that run-out detected with my RCBS tool (or a Sinclair) after a mandrel expansion,would depend on case thickness variation around the neck. So then to fix that variation (and to promote even bullet release upon firing....an outside reamer is another "necessary" step. Then we have a case for benchresting....and forget speedy reloading. Seems the only win-win is......sloooww.

BTW, I screwed in my RCBS Gold Medal Seater last night (in the Summit) and seated a test round I (one I had "over-worked" to .001"). Interesting. I lost a thou. Now measures .002. Not bad for a non-Redding/Forster seater. No cheaper, but it was sure fun to just drop it in from a window. This is a different design from their old "competition dies" I'll post a video of it working soon.

The Gold Medal is designed for progressives, and it just about does away with the need for a rifle bullet feeder and gives progressives a tool closer to a production straight line seating.

 

[Bart B.]

It cost me 10 minutes time with each one using a 1/4" wood dowel split at one end with 600 grit emery paper on it passed in and out of the die that was chucked up in a lathe. Any 'smith could do that, I hope.

One cause of case necks being more bent after bullet seating than before is the shape of the case mouth at its edge. After trimming, a ragged edge is left on the inside. Traditional deburring tools remove that one and put smaller ones at each new edge on that angled surface. It's the inside one that the problem. The smaller the case mouth is than the bullet diameter, that sharp edge puts resistance on bullets going into the case mouth. Too much resistance makes the thinner side of the case neck and shoulder give way and push back bending the case neck even more.

Solution? Make that inside edge on the case mouth rounder and smooth. After deburring with a conventional tool, put a No. 5 Easy Out in and turn it clockwise to debur that edge. Then run the case mouth over a bore brush spinning in a drill press; a few times back and forth will very nicely round that inside edge of the case mouth. Much less resistance hereafter and case necks retain their tiny angle to the case body axis. Sizing cases so their mouth diameter's a bit bigger helps, too.

 

[Unclenick]

GWS,

I took your data and averaged the changes in runout for all 5 rounds, then took the differences between each successive sizing step. The result, with mils meaning thousandths of an inch in this case, was:

                   No sizing  Sizing 1  Sizing 2  Sizing 3  Sizing 4  Sizing 5
Step:                  1         2         3         4         5         6
Avg. runout in mils:  5.0       3.7       2.7      1.825      1.7       1.0
Improvement in mils:   —  1.300  —  1.000  —  0.875  —  0.125  —  0.700

Except for the small change between steps 4 and 5, there is a very steady logarithmic reduction of improvement with each sizing step, which you would expect because there is less improvement to make with each pass. There is no indication I can see that rotating the case did anything two additional unrotated sizing operations would not be expected to do.

…Of course expander pulling got even easier with each successive sizing…

That supports my burnishing theory. You are also burnishing the motor mica into the brass surface, reducing pull on the neck each time. The uneven neck thickness Bart referred to is also going to be a factor. You are probably nudging it a little more to the side with each pass, tending to line it up with the more axial neck position. The same thing happens when you lap a bore irregularity under a heavy-handed dovetail cut. The part of the bore that's out of line with the rest gets rubbed harder by the lap. In this case any part of the brass that isn't on-axis gets more burnishing pressure from the expander, which has the rest of the neck trying to keep it lined up.

Bart's point on the burr edge is another good one. I once seated then pulled a moly-coated bullet from a freshly trimmed and chamferred case and there was no remaining trace of the moly below where the bullet met the chamfer. I was scraped as clean as a whistle. Burnishing the wire edge off the case chamfer fixed that. I hadn't yet got the E-Z out idea from Bart at that time, so I just sharpened a dowel like a pencil and spun that against the case mouth with a drill. That worked, but needed constant resharpening, where the E-Z out is a permanent tool. But another thing I tried that worked was running the case mouth over the carbide expander in my sizing die a couple of times. Either way, that stopped scraping moly, so the drag was gone, too.

By the way, if you examine commercially loaded ammo closely, it's not uncommon to find a little scraped copper where the case mouth meets the bullet. Just keep an eye out for it. The cause is the same as with scraping moly.

Bart's also answered why you can't get below 0.001" runout. Take a steel straight edge and lay it along the side of each case and look at the cracks of light that appear where the wall isn't straight. Rotate the case and you will see these light cracks change size and position. Occasionally you find one that is uniform all around, but they are the exception. Most have some degree of unevenness, and that is what is meant by a "banana shaped case". It's one with side walls that aren't straight and bulge more on one side than another, putting a slight curve into it.

Lots of guys lap the way Bart described. You can cut a little faster and need less feel and technique to keep the cutting randomized with a commercial hone. You can use a Flex Hone the right size. They can be had for around $10-$12 from here. Call the maker for help picking out the best size and watch their videos on how these tools are used. If you buy from the company directly you pay MSRP, while the second source, when they have the size, is between half and three quarters of that price. You can slug the die neck to learn its size, or you can use a pin gauge or a small hole transfer gauge to track your progress.

John Feamster, writing in The Precision Shooting Reloading Guide, compared ammo off the standard RCBS sizing and seating die set to ammo off the RCBS Competition die set, and after seating 100 rounds with each, actually got somewhat better results from the standard set. He also compared 50 rounds seated with an RCBS standard seater on a Dillon 550B press to 50 seated with a Wilson seater die on an arbor press, and got better results with the standard RCBS die on the Dillon press. Things don't always work out as expected. And this book was published in 1995, so if the die design changed it may no longer be a valid result.

Feamster did use a rubber O-ring between the lock ring/nut and the press with the sizing dies to let them have a little wiggle room. The Lee lock rings do essentially the same thing if you don't make them dead tight. I've had mixed results experimenting with this and concluded I needed to lap the press and die threads smooth and use a little high pressure lube on them to get the full effect. STP works fine.

I've never tried mixing STP with Hoppe's, but I have mixed it with odorless mineral spirits and Kroil. Either thins it. They may trouble your spouse's olfactory senses less than #9, though they won't clean powder residue off as well. The mineral spirits are particularly slow to affect powder carbon and graphite.

 

[Bart B.]

One other way to measure sized case uniformity is to use a clean full length sizing die with its decapping stem removed. Once it and cases have all the lube cleaned out and off, gently drop a sized case in it then measure how far out of the die the case head is. Cases that go further into the die have smaller body diameters from the shoulder back. Cases with more body taper and longer necks may "bottom out" when their mouth stops at the die's shoulder-neck juncture.

Turning a case in the die often finds a tight orientation at one or two places proving the die and case are not perfectly round on their touching surfaces. Cases usually drop further in the die where they don't bind up a tiny bit.

 

[GWS]

Bart said: It cost me 10 minutes time with each one using a 1/4" wood dowel split at one end with 600 grit emery paper on it passed in and out of the die that was chucked up in a lathe. Any 'smith could do that, I hope.

I have a drill press, but no lathe. Or if the hone Uncle Nick suggests will work then all I need is a padded vice?....would just have to determine the size needed and the target size. So a measurement with calipers on a seated round using that brass, then subtracting .002 should give me the target, right? Then why plug the bore as Uncle Nick suggests. Not being a machinist I don't have expensive tools like pin or small hole transfer gauges, so I wouldn't be able to check the progress so I suppose repeated plugging may be the only way...and that sounds fun. The other thing I would be unsure about is accounting for the brass spring-back factor in the neck. This is where I think I'm over my head, gentlemen, unless I'm over analyzing.

I use the Forster trimmer with their 3-way carbide cutter. I think I understand you....you mean the inner edge at the bottom of the newly cut chamfer. So the easy-out just smooths the new transition to the neck. That's simple enough to try.....ha ha, what's another step at this point.

Except for the small change between steps 4 and 5, there is a very steady logarithmic reduction of improvement with each sizing step, which you would expect because there is less improvement to make with each pass. There is no indication I can see that rotating the case did anything two additional unrotated sizing operations would not be expected to do.

I agree with most of that, except that I felt the non-rotated steps slowed me down because I could get to .001 without them if I just rotated immediately. And less work hardening with the three sizings vs 6 or 7. I reported that in the first thread, quoted below:

A sixth case I simplified. Presized runout was .004" and first sizing was .005. I immediately rotated the case 1/3, sized, rotated 2/3, sized, and measured once. Run-out was .001"

That supports my burnishing theory. You are also burnishing the motor mica into the brass surface, reducing pull on the neck each time. The uneven neck thickness Bart referred to is also going to be a factor. You are probably nudging it a little more to the side with each pass, tending to line it up with the more axial neck position. The same thing happens when you lap a bore irregularity under a heavy-handed dovetail cut. The part of the bore that's out of line with the rest gets rubbed harder by the lap. In this case any part of the brass that isn't on-axis gets more burnishing pressure from the expander, which has the rest of the neck trying to keep it lined up.

That's an interesting theory....and possibly right.

The following about Feamster is interesting indeed!

Feamster did use a rubber O-ring between the lock ring/nut and the press with the sizing dies to let them have a little wiggle room. The Lee lock rings do essentially the same thing if you don't make them dead tight. I've had mixed results experimenting with this and concluded I needed to lap the press and die threads smooth and use a little high pressure lube on them to get the full effect. STP works fine.

Many years ago (close to 40) I read an article in Handloader Magazine, where the writer insisted that one could get better alignment between die and shell holder by loosening the spring that keeps the shell holder. And I've always done that until recently when I made a case kicker for my Rock Chucker and it needed a tighter shellholder to keep it from rotating on me as I fed brass quickly during depriming operations before wet tumbling. I may have to loosen it up some.

Not sure what you are doing with lapping the press and die threads smooth, and why the high pressure lube? How old is your press threads? After 43 years mine are pretty smooth. Well I guess the die is pretty new. I guess I can see that burrs might worsen alignment. I was taught early on to tighten my dies only with pressure on it from the cammed over shellholder to keep the mating die and shellholder surfaces parallel....a loose shellholder would then provide some side to side wiggle room to finish the alignment. So has all that become out of favor now?

I'll have to buy some STP......that's worth a try.....even if it is harder to clean up. As for Imperial....I'm done with that. Only explanation for my experience with that is when the going gets rough, Imperial quits. Who would have thought that super clean and shiny brass would stop it cold.

 

[Unclenick]

I agree with most of that, except that I felt the non-rotated steps slowed me down because I could get to .001 without them if I just rotated immediately.

Did you test it the same way? It looked to me from the plot like two more unrotated sizing steps would have landed you in the same place the last two rotated ones did. That's why I suggested rotating didn't look like it was getting you anything. But if you think you can get faster results with rotating, that's easy to verify. Just find five cases with close to the same average pre-sizing runout you started with in the last test and use the rotating exclusively and see what happens by step 6. If the improvement has flat lined before you get there, that's your proof.

Yes, you can use cases as your slug. It's them you want to resize, ultimately, anyway, so they are the acid test. It's just that you have to stop and clean the die completely, put it in a press and then put a few lubed cases through it to check. With the gauge you just withdraw the hone and push a cleaning patch or two through to clear loose grit and oil and then measure with the gauge or tap a pure lead slug through. Repeat until you are half way to what you expect your minimum amount of neck opening up to be. A that point, clean the die and check by sizing a few cases. Repeat. That's an old machinist's trick, taking off only half the metal you think you need to remove at a time. It prevents overshooting the mark, which matters as you can't put metal back on very conveniently.

You can get a 0.3125"-0.500" telescoping small hole transfer gauge for just under $12 at Enco. They also have a full set, 0.125"-0.500", of split half sphere gauges for $25, if you think you might ever want to tackle something smaller than .30 Caliber. These tools turn out to be pretty useful for things like checking cylinder chamber throats in revolvers and bore diameters in barrels with even numbers of lands. Slugging is more precise, but you also need to be using a micrometer with 0.0001" resolution to see the advantage of the slug. To be frank, you get more reliable readings from a micrometer for what you are doing, too.

You also probably want to size the hole to give you your minimum ID with a freshly annealed case, as the softer necks will spring back less, being less work-hardened. That way a hardened one may not spring back too much. I would start there, then widen it more if you find your most used and unannealed cases are coming out smaller than they need to be. Ideally, of course, you'd want a number of dies, like Bart has, each maybe a thousandth apart so you can always find one that produces a good ID, regardless of neck wall thickness and loading history. Also, if you intend to do any neck turning, do that first.

Regarding the press threads, as you might imagine, an imperfectly perpendicular thread axis inside a lock ring can cause the die to be slightly cocked when the ring is tightened. Feamster's method was simply to slip an O-ring over the die thread to sit between the locking ring and the press, then didn't tighten down too hard. A Lee lock ring not tightened 100% will do the same thing, but with less adjustment range. This arrangement tends to let the triangular profiles of the press and die threads self-align coaxially. It also allows for slight tilting alignment. It's just giving self-alignment an additional degree of freedom, same as a floating reamer holder does for rifle chambering.

When I first tried this, I didn't get a clear improvement. But I was reminded of something a tool maker I used to work with liked to say: "Only God is perfect. Everything else has tolerances." The press threads seemed pretty smooth and clean and well-fitting, but I lapped them to a polish using a Redding die's threads as the male lap, and then lubed them with lithium grease to help them slip. That seemed to give me a little less runout on finished rounds. I don't have a statistic for you, but my memory says it was around 0.001"-0.002" improvement on .30-06 case (Feamster was working with .308 Winchester). I switched to using a Forster Co-ax press for precision rifle loading years ago, and it doesn't have a die thread so I haven't used the method for some time.

When cases you have start out fired by an unknown gun, they can be large enough that you'd find running them through a standard sizing die before running them through a small base die will save you some effort. It's not worth buying the second die if the SB is the only one you have, and since you've solved the lube problem with it, but I think it explains the extreme effort you encountered.

STP is cheap at Wally World. Just the standard treatment in the blue bottle. Less than $1.50 last time I got any. I'll note that a few folks have also mentioned switching to lithium grease as a case lube. You can usually get it in a plastic squeeze tube or in a plastic tub at Lowe's or at an auto supply store. Lowe's sells a squeeze tube of Ultra Lube white lithium grease. I haven't tried that brand yet in a sizing die (I hate sizing die experiments, having stuck cases before), but I can tell you it's extremely slick in other applications I've played with it in. It's a vegetable-based product and claims to be four times more slippery than its petroleum-based competition. I just haven't decided which die to test this claim in yet.