Headspace questions

[jason75979]

After what I consider a "near miss" during a recent trip to the range I'm here to ask a couple of questions.
Can a casing with excessive headspace be resized back to SAAMI specs? If so, how?
And in case you're wondering, I failed to check the headspacing on some 30-06 brass before reloading. Stupid mistake caused by distractions. Distractions were the very reason I built a separate building away from the house to reload in.

 

[SL1]

Basically, you need to move the shoulder forward without stretching the case too much.

There are a few ways to do that.

The difficult one is to make a "false shoulder" on the case neck by first expanding the neck to a larger caliber and then resizing it with the '06 die set to the proper headspace. That leaves an enlarged section of the neck to hold the case back against the breach when the cartridge is chambered, and prevents the case from stretching when fired. When fired with a normal load, the shoulder blows-out to the proper position. This is one method often used by "wildcatters" to make brass for a cartridge that they are developing.

The easy way is sometimes frowned-upon, because it does leave the possibility of stretching the brass too much. That is to make a low-powered load that is sufficient to "blow the shoulder forward," but not so high powered that it makes the brass grab the chamber wall tighly enough so that the case can't slip back without stretching. So, actually, instead of the shoulder going forward, the back of the neck expands to make new shoulder material. The case should actually get shorter instead of longer. Oiling the outside of the cases will help with that, but often isn't necessary. Figuring-out the proper load may require some trial-and-error unless you can get some advice here on how others have succeeded. I don't shoot '06s, so I will have to leave that to others. However, I will tell you that when I make .30 Herrett cases for my Contender, I use a mid-powered load with no lube on the cases to fully expand the case bodies after their initial forming. (I am not moving the shoulder location, but I am drawing brass from the necks to fill-out the case bodies. That typically causes the cases to get about 0.005" SHORTER. However, when I use full power loads in the same gun, those cases will get a few thousandths LONGER on each reloading, mainly because the Contender frame is much more "springy" than a bolt action, and the cases actually do stretch with those loads.

Finally, if the headspace error is not too large, some here may suggest that you can simply fire the brass and stretch it a little without causing an IMMEDIATE safety problem. Whether that causes a problem later is still a matter for consideration. If your brass is typically thrown away at its "end-of-life" because it is reaching incipient head separation, then this last approach would make that happen with fewer than usual reloadings. On the other hand, if you typically throw your brass away because of neck splits, then this technique MIGHT make the incipient head seperation become the reason for discarding this particular set of brass some time in the future. So, if you don't typically check the insides of your fired cases for thinning rings, you probably should with these cases.

SL1

 

[Jim243]

Jason

I am sitting here scratching my head as to what your problem actually is.

"Near Miss"?? due to head space?? or something else like no powder or too much??

The headspace shown in your photo, while not perfect should not be a problem. I have about the same on my 243's. That looks like a un-fired new case.

The first thing is that if you have fire formed those cases, that is the headspace of your rifle. It is not unusual for a rifle's headspace to be 0.02 off from the SAMMI standard which is what is used on the gauge. It is more of a problem if the headspace is too long and the bolt will not close.

If you are setting your shoulders too far down then just raise your die a half turn up when you are resizing your cases and check with your gauge to set your die. I personally think you will find that the headspace of your rifle is what is shown on your photo.

Those cases are safe to use for your reload if everything else on them is OK.

What it has to do with a "Near Miss" I do not know but would like to find out.

Jim

 

[jason75979]

Jim, I only measure with my scale (RCBS 505) and pay very close attention to charge weights. This was a second loading of the brass after neck sizing only. I'm still new to this but understand what you're saying about the brass being fireformed to my rifle. That coincides with everything I've read. I was loading 180 Accubonds in winchester cases with 58 gr. RL 22 and WLR primers, just under a 100% load. I may be mis-diagnosing the problem. And any help with a more accurate diagnosis is greatly appreciated.
But here are the reasons I consider the incident to be a near miss. You can't see from the pic, but there's actually a hole on the outter rim of the primer inside the crater.

The crater in the bolt face was also caused by the malfunction.

Everything seemed fine. The bolt closed easily, the handle fell smoothly and easily, even opened easily although there was an ever so slight resistance on the rise.

 

[jason75979]

After further inspection of the case I found lands marks on the mouth.

I re-measured the fired case and come up with 2.491?? Still under maximum length, but all these cases were trimmed to 2.484 prior to loading.

 

[243winxb]

WLR

Another WLR primer> http://www.thehighroad.org/showthread.php?p=7874757#post7874757

 

[Jimro]

Jason, looking through this thread leads me to the only plausible sequence of events I can think of.

1, a round that is short by a few thousandths gets loaded into your chamber. There is a gap in headspace because of the claw extractor holding the cartridge against the bolt face leaving the shoulder unsupported.

2, the primer ignites and lights off that slow RL-22 causing a pressure spike that expands the brass forward and shoves the neck into the lands. Whether it was the primer alone that expanded the brass or not is immaterial.

3, the powder continues to burn, but now it takes more pressure to dislodge the bullet than before, causing a higher than normal pressure spike.

4, the primer cup fails before the bullet leaves the bore causing a jet of hot gas to damage your bolt face.

I bet dollars to donuts that you'll find a crack on the inside of your brass if you do the paper clip or dental tool inspection. Please do an inspection and let us know.

Jimro

 

[Jim243]

I have to agree with 243winxb, it looks like a bad primer.

In the photo of the neck of your case, I do not see any lines or groves but a crimp that looks like it was done buy a Lee factory crimp die. Too heavy a crimp will raise the pressure in the case and cause a primer blow out. Use a medium crimp or light crimp in the future.

The hit on the primer is clean and perfect. As to the blacking around the primer, I would guess that they were not put in hard enough to seal the primer in the pocket or the pocket was oversized and did not seal the primer completely. If you are hand priming the cases, use a little more pressure on those primers.

As to bolt lift, there should be a little resistance when opening the bolt, problem is when there is a lot of resistance in getting the bolt open.

Jim

 

[jason75979]

Jim, no crimp what so ever. I prime with my press also. The marks around the mouth are broken just as the lands and grooves are.
I plan on shortly, sacrificing one of the 3 rounds fired. The other 12 have been pulled already.

 

[Jim243]

The marks around the mouth are broken just as the lands and grooves are.

No way can that be rifling of your barrel on the case mouth.

1. The datum of the bullet would not let the case be pushed that far up.

2. The throat of your chamber does not have rifling in it.

3. The bullet will be 0.01 or 0.02 larger than the barrel and any lines and groves will appear on the bullet and not the case. The straight lines on the indents of the mouth of the case are from crimps not rifling.

Jim

 

[jason75979]

I'm really not trying to sound argumentative, but, I did not crimp this ammo. I do not crimp any rounds loaded for rifle.

 

[Jimro]

Jim243,

I've never seen any crimp marks survive firing, clearly that brass was pressed against something upon firing.

Jason75979, any signs of looming case separation in that brass?

Jimro

 

[Jim243]

Jason

To a point I agree with you, but then you have something stuck in your chamber that should not be there? A broken case mouth??

I do not know why you get those marks on the case mouth but it is not rifling?

Jim

 

[243winxb]

Primer is defective IMO. I have had 1. Gas leaking between the primer & brass may cause it also. Check for loose primer pockets when seating new primers. The marks on the case mouth are left over from a "factory" crimp, if the brass is from new factory ammo? If not factory ammo brass, then i dont know. The head space is a little on the short side, but would have to be over .010" to have a case head separation on the firing.

 

[wncchester]

Naw Jason, you didn't even come close to any harm. Your case suggests a full but certainly not excessive charge.

Your primer blew out at the radius of the cup due to a defect in the cup itself - such cup blow outs aren't common but they really aren't all that rare either - therefore, it is NOT an indicator of excessive pressure. You may experience a few more from that manufactoring lot number so if you take that blown primer/case and the remainder of your primers back to your dealer you should be able to get them exchanged. Or do what I do with them, use that batch of primers in lower pressure ammo for lever rifles.

The blackened ring around the primer pocket is the result of the released gases. The unsightly burn pit and circle the hot gas cut in your bolt face is cosmetic, it will make no difference in the safety or accuracy of your rifle.

The crimp marks on your case mouths are from the original factory loading. I've never seen those crimp marks dissappear even after several reloading cycles.

The live cartridge sitting in your Wilson gage looks about like what I would expect with a new factory round, meaning if it's a new or previously neck sized case it's unlikely to produce a head seperation in the next firing. Just shoot it and adjust your FL die properly next time.

Your nice 'drop in' Wilson case gage only tells you if your ammo matches SAAMI tolerances and will work in any chamber ever made in that caliber but it certainly isn't a way to gage your handloaded ammo for a precise custom fit. For that, get a Hornady LnL case "headspace" gage that fits on the jaws of a precision dial caliper to measure your 'before' and 'after' FL resized shoulder locations - there is no reason to move the shoulder back passed the fired location for bolt rifles and doing it that way insures you will have the least possible case stretching. (Other gages can do the same thing but Hornady's is the most versatile and cost effective.)

Headspace is in the chamber as it's built by the maker; reloaders can't do anything about headspace. However, it is very rare that the actual headspace means anything to a reloader who knows what he's doing even if it's 'excessive' because he adjusts for it. What we have loosely come to call adjusting our 'cartridge headspace' is no more than resizing our case shoulders to fit the headspace we have. (And we do it the same way for all bottleneck cases, no matter if they have a rim or belt.)

Excellant photos, by the way.

 

[mrawesome22]

That gauge just means they will fit in any 308Win ever made.

Bad primer or loose pocket.

Definitely not rifling marks on the case. Your rounds would never chamber if the throat wws that short. Looks like no crimp I have ever saw. My only guess would be an object stuck in the chamber, as mentioned earlier.

 

[amathis]

I've never seen any crimp marks survive firing, clearly that brass was pressed against something upon firing.

Those are not rifling marks or any other marks for that mater. IMO they are factory crimp marks.

This picture came from 300WM brass that has been fired 3+ times. I don't crimp either but there is still the appearance of a crimp when it came new from the factory. . . . . .

 

[jason75979]

Okay, no foreign objects in chamber or bore. Amathis has helped to discount any contact with the lands. So, a "defective" primer is the general consensus which is good to know.
I've made a mountain out of a mole hill.
Thank you all for your patience and help.

 

[William T. Watts]

Unless I am missing something you made no mention of total times the case has been fired? The way you describe neck sizing and fired twice sounds like the case has been fired at least three times with a near max load that could have loosened the primer pocket. Your suppling just enough information as to confuse the issue. Additionally your picture of the L.E. Wilson cartridge case gage with primed/loaded round inserted in the gage shows your moving the shoulder back to much, the lower step of the gage is minimum. Additionally if you have a factory round drop it in your gage for comparison. Any time you have a primer failure it's good thing to check and double check everything, I would pitch the brass your using now and start with a box of factory ammo and start over and forget about loading up at the upper end until you gain more understanding of the loading process. William

 

[jason75979]

William, 2nd reloading meant new winchester brass FL sized, shot in my rifle, and then neck sized for this particular loading.
And I was no where in the vicinity of a max load.
Primers felt good going in.....not too loose, not to tight.