Headspace comparator question..
- Thread starter 1stmar
- Start date
I can't remember the more accurate term, but call the distance from the case head to the datum line isn't headspace.
But for what you asked, I find using a cartridge that has been fired multiple time with moderate loads until bolt closure just starts to increase without sizing, give me the most accurate standard. I keep that cartridge for that rifle and if it is a bolt action, I set the shoulder back about 0.002" when I adjust my sizing die.
A single firing of a full sized cartridge will not normally result in fired brass that is the full length to fill the chamber. So that is probably why your measurements vary 0.003".
But for what you asked, I find using a cartridge that has been fired multiple time with moderate loads until bolt closure just starts to increase without sizing, give me the most accurate standard. I keep that cartridge for that rifle and if it is a bolt action, I set the shoulder back about 0.002" when I adjust my sizing die.
A single firing of a full sized cartridge will not normally result in fired brass that is the full length to fill the chamber. So that is probably why your measurements vary 0.003".
I measure 10-20 cases fired in my rifle and take an average plus note the longest several cases. For a particular bolt rifle I normally size back .002" from the longest of the cases. That's just for normal hunting rifles not match rifles. For semi-autos I take the longest measured shoulders and push them back trying for .003". Now if the ammunition I load is to be used in several rifles I make sure they will chamber in all of them. Some just recommend using your rifles chamber as a gauge and to make sure the bolt will close with no resistance but I do like either the RCBS Precision Mic or Hornady's Headspace Gauge Set. Different brands of brass have more or less spring back after firing, different load levels will make a difference on the amount of shoulder expansion, and cases fired multiple times versus once fired can make a difference on your shoulder measurements.
That's what I thought, after initial firing the case either doesn't expand fully or partially contracts (guessing) it's not until subsequent firings that the case maintains/expands fully.. Hence why you can get multiple firings from neck sizing before having to fl size. That sound about right?
Yes, that's about right.
People full length sizing .308 Win cases reducing the fired case body diameter and setting the shoulder back the same amount, about .002", have easily got several dozen reloads per case using normal, max peak pressure loads. They've also got best accuracy doing this compared to neck only sizing of fired cases.
People full length sizing .308 Win cases reducing the fired case body diameter and setting the shoulder back the same amount, about .002", have easily got several dozen reloads per case using normal, max peak pressure loads. They've also got best accuracy doing this compared to neck only sizing of fired cases.
A reloader that is familiar with reloading understands the shell holder has a deck height is .125” and the dies ability to return a case to minimum length/full length sized is determined by the distance from the deck of the shell holder to the shoulder of the die, or as some say without daylight between the top of the shell holder and bottom of the die. When I want to know if the press, die and shell holder won I use the feeler gage. I am familiar with dies and shell holders, when I compare the length of a fired case from the case head to the shoulder with the know length of a chamber from the bolt face to the shoulder of the chamber I adjust the die off the shell holder with a feeler gage.
If I was a fire former and I used a case comparator I would still adjust the die off the shell holder with the feeler gage.
Measuring a case length from the shoulder to the case is a method/technique I use when purchasing fired cases. I want cases that have been fired in long/trashy chambers, minimum length/short cases from the shoulder to the case head may not allow me to off set the length of the chamber from the shoulder to the case head, I am the fan of cutting down on all that case travel, deterring the length of the case in thousandths is so easy when the die is adjustable with threads in the press and the reloader understand the relationship between the length of the case from the shoulder to the case head and the gap between the top of the shell holder and bottom of the die.
F. Guffey
If I was a fire former and I used a case comparator I would still adjust the die off the shell holder with the feeler gage.
Measuring a case length from the shoulder to the case is a method/technique I use when purchasing fired cases. I want cases that have been fired in long/trashy chambers, minimum length/short cases from the shoulder to the case head may not allow me to off set the length of the chamber from the shoulder to the case head, I am the fan of cutting down on all that case travel, deterring the length of the case in thousandths is so easy when the die is adjustable with threads in the press and the reloader understand the relationship between the length of the case from the shoulder to the case head and the gap between the top of the shell holder and bottom of the die.
F. Guffey
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Good question.... on bolt guns, it's simple enough to tell by resistance of the bolt.
Despite what I guess would be a bit shortened brass life, I've always bumped the shoulders more on our gas guns because of concern of not bumping enough and causing extraction issues.
Wouldn't one see hard extractor marks if cases weren't being sized adequately?
Despite what I guess would be a bit shortened brass life, I've always bumped the shoulders more on our gas guns because of concern of not bumping enough and causing extraction issues.
Wouldn't one see hard extractor marks if cases weren't being sized adequately?
Sierra - Reloading for Semi-Autos and Service Rifles
Reloading for Semi-Autos and Service Rifles http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm
Reloading for Semi-Autos and Service Rifles http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm
Yes, but what if I did not know the length of the chamber from the shoulder back to the bolt face, knowing the length of the chamber separates fire formers from case formers. Then there are smith that cut chambers, A smith that cuts a chamber should be able tell the new owner the length of the chamber in thousandths from the shoulder/datum to the bolt face. Instead the new owner is told the chamber is within SAAMI specifications.
If I want to know the length of a 308 chamber I form 30/06 cases to fit the 308 W chamber. How can a reloader that know what they are doing miss? The reloader has 389 chances to get it correct because the 30/06 shoulder is ahead of the 308 W shoulder.389", For the 30/06 there is the 280 Remington, the 280 Remington shoulder is ahead of the 30/06 shoulder .051".
Again, I have an Eddystone M1917 with a long chamber from the shoulder to the bolt face, when forming cases for that chamber I adjust the die off the shell holder .014", that is beyond anything a redding competition shell holder can do, I could use a Redding competition + .010" shell holder then adjust the die off the shell holder .004"/
Bump, I have no allusion about bumping, when I size/form a case the shoulder does not move, it is erased, the new shoulder is formed in the process.
F. Guffey
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tobnpr asks: wouldn't one see hard extractor marks if cases weren't being sized adequately?
That's what I've observed a time or two. Some folks shooting neck only sized cases from bolt guns then reloading them to shoot in Garands have cases ended up with linear scratch marks on case bodies and deep scratches from extractors pulling on the fired case rims. Evidence to me that the case hadn't shrunk back enough from the chamber walls before the bolt started back.
In one instance, I took several of those reloads and tried to chamber them with finger pressure in .30 caliber Garands. Some went all the way in easy and others with different amounts of resistance. But the force of the op rod spring returning the bolt back into battery was enough to chamber the round when it was single-loaded. A lot of force was needed to pull the op rod and bolt back to eject those live rounds as the case body was tightly wedged into the chamber
That's what I've observed a time or two. Some folks shooting neck only sized cases from bolt guns then reloading them to shoot in Garands have cases ended up with linear scratch marks on case bodies and deep scratches from extractors pulling on the fired case rims. Evidence to me that the case hadn't shrunk back enough from the chamber walls before the bolt started back.
In one instance, I took several of those reloads and tried to chamber them with finger pressure in .30 caliber Garands. Some went all the way in easy and others with different amounts of resistance. But the force of the op rod spring returning the bolt back into battery was enough to chamber the round when it was single-loaded. A lot of force was needed to pull the op rod and bolt back to eject those live rounds as the case body was tightly wedged into the chamber
There is a thread here at TFL that ask . What's your favorite reloading tool ? I did not post in that thread but now that I think about it . I'd say it's my feeler gages . I can get all my 308 cases with in .001 of each other just by slipping the right size feeler gage in between the the case and shell holder when sizing the case http://imageshack.com/a/img836/7355/k441.jpg. Meaning I size a case and it measures 1.6235 but I'm looking for 1.6220 . I just slip a .0015 feeler gage in between the case and the shell holder lifting the case up .0015 then size it again . This almost always puts the shoulder to 1.622 and at worse 1.6225 . If I want to get rit of that .0005 I add just a tad extra sizing wax and size again . It never seems to be needed to knock it back that extra .0005 but it is pretty cool how easy it is to manipulate the size of the brass by using feeler gages and sizing wax .
They do make shell holders that do the same thing but the feeler gages just slip in and out wth out having to change the shell holder or remove the brass . Although I have not used the different sized shell holders I'd think the feeler gage thing is much easier and quicker and they only cosy $7 at your local auto parts store .
They do make shell holders that do the same thing but the feeler gages just slip in and out wth out having to change the shell holder or remove the brass . Although I have not used the different sized shell holders I'd think the feeler gage thing is much easier and quicker and they only cosy $7 at your local auto parts store .
What's your reason for not screwing the die down .0015"? That's about 1/8" circumference shift of the lock ring to the die. Then you wouldn't have to have two tools in your hands; just one, the press handle.
You could size a batch of cases twice as fast with resonable dexterity in your hands and fingers. As you hold an unsized lubed case 'tween two fingers, pull the sized one out of the lowered shellholder with the adjacent pair of fingers, then slide the lubed one into the shellholder. While your left hand puts the sized case in a "sized" box, your right hand's operating the press sizing the case. On the ram's down stroke, your left hand's got a new lubed case headed for the shell holder. Then repeat this 'till you're done.
You could size a batch of cases twice as fast with resonable dexterity in your hands and fingers. As you hold an unsized lubed case 'tween two fingers, pull the sized one out of the lowered shellholder with the adjacent pair of fingers, then slide the lubed one into the shellholder. While your left hand puts the sized case in a "sized" box, your right hand's operating the press sizing the case. On the ram's down stroke, your left hand's got a new lubed case headed for the shell holder. Then repeat this 'till you're done.
Brian Pfleuger
Moderator Emeritus
I can see using feeler gauges to adjust the die, I have done that. I can't see why I would want to actually size the brass with a feeler gauge. If you need 0.015 at full stroke, find your 0.015 gauge, unscrew the die, raise the ram, put the gauge on the shellholder, screw in the die and you're adjusted.
Simple answer to both of you is . I already have my die set to size 90% of the cases perfect . I use them when I have those stubborn cases that don't quite want to bump back were I want it . I ask you why unlock screw down then lock again for one case just to have to put it back for the next 15 cases . What about not putting it back and the next case you size is .0015 shorter . Now instead of a .002 bump you get a .0035 . Sure seems like a lot less work and time to pop a feeler gage in real quick . Kapeesh 
I should ad that those were just general numbers . Most of the time when I need the feeler gage it's because the case is not likely to chamber Because it's right at the max length . I don't test each one in the chamber . I just make sure they are bumped back .0015 to .0025 from my fired brass . I have had to use the .0025 gage more then once to bump a shoulder where I wanted it . I remeber using the .003 once as well . It seems to happen with brass thats been loaded a few times . My thought is they are worked a bit more and have a little more spring back then good soft shoulders . This is more of what I'm thinking is going on when it comes to some shoulders not bumping back as far as others . I'm not really sure why the cases don't size the same every time .
I should ad that those were just general numbers . Most of the time when I need the feeler gage it's because the case is not likely to chamber Because it's right at the max length . I don't test each one in the chamber . I just make sure they are bumped back .0015 to .0025 from my fired brass . I have had to use the .0025 gage more then once to bump a shoulder where I wanted it . I remeber using the .003 once as well . It seems to happen with brass thats been loaded a few times . My thought is they are worked a bit more and have a little more spring back then good soft shoulders . This is more of what I'm thinking is going on when it comes to some shoulders not bumping back as far as others . I'm not really sure why the cases don't size the same every time .
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