Steve Donlon
Gold $$ Contributor
I missed that part about shooting the brass in 2 different rifles! That most likely could be a big problem if the chambers were not the same.
Case head separation
- Thread starter moe africa
- Start date
Tim Singleton
Gold $$ Contributor
This very well is the problem!
If he is setting his shoulder from rhat gauge instead of the fired brass
I used the gauge in conjunction with the taking out the fire control , and using the chamber
Either way it's new brass time. On my .300 Win Mag, which are notorious for extremely short brass, headspace wise, I necked up all the brass to .33 caliber for the first firing and cases formed perfectly. I set the headspace by gradually lowering the die until cases would chamber slightly tight. You could do the same if needed. Stick to .001 shoulder bump and you should be fine.
Paul
rwj
Gold $$ Contributor
Most likely that @moe africa removed the firing pin assembly from the bolt, then inserted a case into the chamber to determine if the bolt (less firing pin) would freely close.
AlNyhus
Silver $$ Contributor
moe africa: Here's an easy way to check this out.
-With a fired, unsized case, remove the spent primer. Fired primers will add a couple thou. of fake 'length'.
-Measure the case using a comparator.
-Then size the case with your current die setting.
-Remeasure the case using the comparator.
-The difference is how much you're setting the shoulder back.
In the examples shown, the shoulder is now .002 further 'back'....or .002 shoulder 'bump'.
Check yours and see what you have.
Hope this helps. -Al
-With a fired, unsized case, remove the spent primer. Fired primers will add a couple thou. of fake 'length'.
-Measure the case using a comparator.
-Then size the case with your current die setting.
-Remeasure the case using the comparator.
-The difference is how much you're setting the shoulder back.
In the examples shown, the shoulder is now .002 further 'back'....or .002 shoulder 'bump'.
Check yours and see what you have.
Hope this helps. -Al
bozo699
Gold $$ Contributor
Bill said continually sizing .003 will eventually cause case head separation and K22 agreed with him nothing was said that .002 would. I actually agree and disagree with what Bill said. In theory he is correct, although if you never bump the shoulder back at all and you’re able to get the bolt closed at some point the case will fail. I have some 6BRX cases with over 30 firings on them that was bumped .0005-.001 or as close as I could to that number. It takes a lot of practice and patience to be able to get almost repeatable measurements!… I guarantee you’re not going to grab a caliper and a Stoney point/Hornaday comparator set and immediately be able to read tight tolerances without some time and practice. I have another set of cases with.002 bump with almost as many firings I won’t even tell you how I keep the primers in some of them or the reloading police would be out in full force!… but do I think that if I pushed the shoulder back another .001 for a total .003 that my case life would go from 30+ firings to 7?… not a chance!
Wayne
I do not disagree with your post since you obviously have the results to back it up. It also might depend on if you are annealing.
My experience has been somewhat different. The OP bumps to .003. The question is why? Does he need to bump that much? Because of case inconsistency, caliper and operator error, a .003 bump could actually be .004 or .005. Of course, the reverse could be true.
After my new cases are fired formed to the chamber, I set my die to a zero to .001 bump. In my experience, this produces optimum sizing for my rifles. I think this is because the F/L die also size the radial dimension of the case which is often the culprit in chamber issues.
When I first started measuring bump with a gauge and caliper, I went along with the "herd" and bumped to .002 every time. What I discovered was that my cases started showing incipient head separation after about 10 sizing's. That's when I changed to the reducing the bump realizing I didn't need to bump that much. My cases life improved. I should also add, I do not anneal that this could be contributing factor to my experience being different than yours.
I measure a sample of cases before each sizing to check the fired case head space. I adjust my die accordingly. I use Skip Shim which makes the process easy and simple to make bump adjustments. Most of the time no adjustment is necessary but as case age, sometimes I have to make some adjustments.
I use the Whidden Bump gauge. It's single piece, caliber group specific, with no inserts. I have it permanently mounted on a dedicated caliper. This has significantly improved my measurement repeatability.
Also, as you stated, operator consistency is important to repeatable measurement. Apply consistent pressure to the caliper and rotating the case in the jaws and gauge helps seat the case in alignment.
I have seen considerable variation with the Hornady tool while helping fellow shooters. Those anvils can make it worse since I've seen some that were not cut straight. I solved their problem somewhat by placing match marks on the insert and holder to help consistent alignment and trashed the anvil.
Still, your point is valid, an additional .001 bump should not result in a case life reduction from 30 to 7. By the way, I have never gotten more than 18 firings from my cases in calibers such as 223, 243, 22 240, 308, all bolt rifles.
So he says a .003" bump will cause head failure but a .002" bump never will. Doesn't pass the common sense test.
bozo699
Gold $$ Contributor
If you read my post you will see I totally agree with you
Wayne
Sorry old age creeping up.
J.J. Coe
Silver $$ Contributor
Hey Al, not to change the subject but I have a little hack for that fired primer that's standing proud and nothing available to deprime it. Just use the primer seater and push it back in.......works in a pinch.moe africa: Here's an easy way to check this out.
-With a fired, unsized case, remove the spent primer. Fired primers will add a couple thou. of fake 'length'.
-Measure the case using a comparator.
-Then size the case with your current die setting.
-Remeasure the case using the comparator.
-The difference is how much you're setting the shoulder back.
In the examples shown, the shoulder is now .002 further 'back'....or .002 shoulder 'bump'.
Check yours and see what you have.
Hope this helps. -Al
AlNyhus
Silver $$ Contributor
Great idea, J.J.!
I guess I should have made it plain I was referring to run of the mill brass. Lapua or other higher quality brass may stay the course but I still would not want to bump it that far each time it was sized.
Dolomite
Silver $$ Contributor
I use this sizing brass method. I started with a Forster FL sizing die which really over sized the case down to factory specs which caused the brass to grow in OAL but still maintained the .002 headspace. Switched to a Whidden die which just barely sizes the brass and gets the base more, which stopped the OAL growth.
www.wheeleraccuracy.com
Videos | wheeleraccuracy
Last edited:
bozo699
Gold $$ Contributor
bozo699
Gold $$ Contributor
It’s the best way for sureI use this sizing brass method. I started with a Forster FL sizing die which really over sized the case down to factory specs which caused the brass to grow in OAL. Switched to a Whidden die which just barely sizes the brass and gets the base more.
Videos | wheeleraccuracy
Wayne
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.