Need help - rounds not chambering?

[awpk03s]

I recently started reloading 6.5CM. I have 4 rifles in that chambering, two bolt guns and two semiautomatics.

In load development, I used once fired brass from the bolt gun. Redding FL sizing die, and micrometer seating die.

When testing, in both bolt guns all went smooth, and I settled on a charge weight, and seating 0.015-0.02” off the lands.

Moving on to mass production, I sized all my brass same way as I did originally.... screwed die to top of the shell plate, backed off a little. Now all this once fired brass was from all my rifles, auto and bolt.
Long story short, I made a bunch of rounds, and discovered that a high percentage (half based on my small sample size) will not chamber. Bolt will not close - I could force it maybe, but enough clues that something is wrong.

My hypothesis is that the brass fired by semiautomatics is hosing me up, and perhaps I should be more aggressively sizing/bumping back on the cases...? Is this feasible? I’m probably looking at pulling a bunch of bullets, dumping powder, resizing, and then loading again...? I guess?

 

[Dthomas3523]

I recently started reloading 6.5CM. I have 4 rifles in that chambering, two bolt guns and two semiautomatics.

In load development, I used once fired brass from the bolt gun. Redding FL sizing die, and micrometer seating die.

When testing, in both bolt guns all went smooth, and I settled on a charge weight, and seating 0.015-0.02” off the lands.

Moving on to mass production, I sized all my brass same way as I did originally.... screwed die to top of the shell plate, backed off a little. Now all this once fired brass was from all my rifles, auto and bolt.
Long story short, I made a bunch of rounds, and discovered that a high percentage (half based on my small sample size) will not chamber. Bolt will not close - I could force it maybe, but enough clues that something is wrong.

My hypothesis is that the brass fired by semiautomatics is hosing me up, and perhaps I should be more aggressively sizing/bumping back on the cases...? Is this feasible? I’m probably looking at pulling a bunch of bullets, dumping powder, resizing, and then loading again...? I guess?

You shouldn’t just be running the die down and then backing off a little.

You need to be using caliper/comparator and knowing exactly how much you’re bumping the shoulders. And you should be just bumping enough to chamber properly.

Each rifle may be close enough in measurements to bump them all back to a uniform bump, or you may need different bump for each rifle.

 

[awpk03s]

Thanks... Sounds like a worthy tool investment to make.

 

[NiteQwill]

Did you measure your fired brass at the shoulder? Even if you are FL sizing, you need to measure HOW MUCH you're bumping the shoulder back.

Additionally, I would consider separating brass you fire in your bolt gun vs your semi-auto.

 

[Deleted member 10043]

Didn't we just have a similar thread recently?

 

[awpk03s]

Thanks guys.
I’ll get a gage in to measure the shoulder properly (Found a Wilson one that looks like it will do the trick). In the meantime, will sort what I’ve got and reduce the rounds to bare components again, and then resize properly for the bolt gun chambers respectively, and start over.

 

[awpk03s]

Any input as to which of these would be more suitable? And am I even looking at/for the right stuff? There’s a pretty wide disparity price wise here, so I don’t want to over/under do it...

Redding Instant Indicator Comparator Dial 6.5 Creedmoor

The Redding Instant Indicator Comparator with Dial is useful for quickly comparing headspace and bullet seating depths within 0.001 of an inch. The...

www.midwayusa.com

Hornady Cartridge Ga 6.5 Creedmoor

Hornady Lock-N-Load Cartridge Gauges allow the user to check their cases and ammo to ensure a correct fit in SAAMI chambers. Cut to SAAMI maximum...

www.midwayusa.com

Thanks again everyone.

 

[BCMulx]

Another way to do it is to get to "zero headspace" using a stripped bolt and adjusting your die, then use the stepped redding shell plates to go .002 off. But, with two different rifles, you'd need to make sure that headspace works for both of them, so will be sub-optimal for at least one. Not a gas gun guy, so this is worth what you paid for it.

Good demo here:

 

[BCMulx]

Regarding measurement tools - do you have a set of good digital calipers like a Mitutuyo? If not, you should. You can get bump gages, etc that fit the calipers, same for bullet comparators for measuring CBTO.

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https://www.sinclairintl.com/userdocs/learn/Sinclair_Bump_Gages_Inst.pdf

Sinclair Comparator/Bump Gage Body and Inserts

The Sinclair Comparator/Bump Gage Body, along with various inserts, allow accurate measurements of bullet seating depth and sizing die adjustment. One of the most important skills a handloader can …

panhandleprecision.com

 

[awpk03s]

Aha, yes, I use those inserts to measure bullet ogive, something similar for case shoulder should be the ticket.

 

[spife7980]

Aha, yes, I use those inserts to measure bullet ogive, something similar for case shoulder should be the ticket.

Yep. Hornady and Sinclair both offer the headspace comparator bushings. It’s the way to go, assigning an actual number to each dimension instead of those plunk gauges that are just a pass/fail with no telling what dimension it was that failed.

 

[918v]

Saved you some money:

 

[Jordanwickham]

The general bump for semi auto is different than bolt also. I would at the least segregate bolt brass from semi brass. But you should segregate brass from each rifle unless you know the two bolts were chambered with the same reamer, which I don't know a reason to have done that. Each chamber will be a little bigger / smaller than the other so running one bump for 4 rifles isn't going to be the best experience. If you bump all based on your shortest chambering you'll be running into head separation problems early. All of that sounds like a headache.

 

[awpk03s]

The general bump for semi auto is different than bolt also. I would at the least segregate bolt brass from semi brass. But you should segregate brass from each rifle unless you know the two bolts were chambered with the same reamer, which I don't know a reason to have done that. Each chamber will be a little bigger / smaller than the other so running one bump for 4 rifles isn't going to be the best experience. If you bump all based on your shortest chambering you'll be running into head separation problems early. All of that sounds like a headache.

Thanks! I will keep all fired brass separate from here on out for sure, and size accordingly.

 

[nightman89]

Saved you some money:

View attachment 7372356

Is that a 9mm case?

 

[salks]

Check the size of the brass way down by the rim. Compare the ones that fit and the ones that don't. .001 can make a difference.

 

[918v]

Is that a 9mm case?

.40 S&W case

 

[awpk03s]

Wanted to say thanks again for the help in this thread. I got my Sinclair bump gage in yesterday, and going through my brass, found a variety of different dimensions - explaining my issues.
I’ve already pulled all the bullets from the loaded rounds, and am going to get more scientific with my brass sizing and segregation here going forward and try it again.