Bullet seating depth changes when chambering

[Sleighter]

Hi everyone,

I'm a beginning reloader and have read through the ABC's of Reloading and Hornady's reloading manual a few times and need some advice. I've setup my press correctly (as far as I know) and made about 100 rounds which worked well.

Tonight my brother was asking to see my handgun and instead of dry firing it, I grabbed a some brass that was tumbled and added a bullet (without depriming and without powder) so that I had made a basic "snap cap" type dummy round. He proceeded to chamber, dry fire, eject and re-chamber the dummy round. Each time the bullet would get pushed further into the brass until the tip of the bullet barely was above the brass rim.

I'm concerned that if re-chambering the round is changing the bullet seating depth, that it is changing the first time it's chambered and changing my pressures. Any thoughts?

Is it the lack of powder? Is there not enough crimp? Is it just that it's not meant to be re-chambered repeatedly? Any help and expertise is greatly appreciated.

[Bill Steele]

The combination of the brass you used, the sizing die you used and the bullet you are using conspired to make your neck tension insufficient. What brand of sizer die are you using, what was the headstamp on the brass (R-P, TZZ, Starline and a few others are thin enough that with jacketed bullets and a looser sizing die you won't get enough tension to hold the bullet), what caliber, what type of gun, etc.

In some actions/calibers a little setback is hard to avoid, unless your brass is thick enough or your sizer small enough to assure a coke bottle look with the bullet seated.

If you can give the facts on the above, we can get you set straight.

Oops, just read Scotty's post below and re-read you OP, if you did'nt size the brass, the bullet won't stay put.

[scotty99]

Your case had not yet been through the resizing die (that is the die that de-primes). Besides knocking out the primer, this die also shrinks the diameter of the case back to original spec - typically .002 to .004 smaller than after firing. That little bit of slop in the chamber is what allows the round to feed reliably. Upon firing, the brass expands and seals the chamber, and this is why it must be resized before being reloaded.

Next time you are loading, make yourself some snap caps by seating bullets in unprimed, uncharged, but resized cases, then fill the primer pockets with a little silicone. This makes it obvious they are dummy rounds, and also gives the firing pin something to strike.

To put your mind at ease on the seating issue, next time you are at the range manually run a full mag of ammo through the gun by racking the slide repeatedly, then re-measure the rounds. If you are getting setback, then you need to turn your seating die a little deeper into the press to increase your crimp, and back off the seater a bit to maintain correct OAL.

[Sleighter]

Thanks for the quick and effective suggestions. I don't know why, but i had a mental picture of the resizing die lengthening the brass not reducing the circumference. I'll give that a try and run a full mag through the chamber to check resizing.

Thanks for the silicone suggestion also. I had been thinking of what I could fill the primer pocket with after depriming for my snap caps.

[Bill Steele]

Thanks for the quick and effective suggestions. I don't know why, but i had a mental picture of the resizing die lengthening the brass not reducing the circumference. I'll give that a try and run a full mag through the chamber to check resizing....

Yes, if you didn't run the brass through your sizing die, the bullet generally will not be held very tightly at all. In fact that is what the belling step is all about, after sizing, making the mouth wide wnough so the bullet can start being seated.

What I was referring to was if you had sized and still didn't have enough tension. When I am loading say .45ACP with .451 jacketed bullets, if I am using R-P, TZZ or Starline brass, I always take my Redding Dual Ring sizing die out (which is slightly looser in neck diameter, perfect for loading lead) and replace it my Dillon sizer (as it is a smaller neck diameter). This assures I get enough neck tension to hold the bullet when feeding, etc..

If you are loading for a semi that headspaces on the case mouth like 9mm, 40S&W, 45ACP, etc. the crimp is not meant to hold the bullet from setback. The neck tension is what holds it firm. Most dies you buy today will size brass down such that your reloads will have a little coke bottle shape when completed, this will guarentee you are not getting setback when feeding.

Good luck, have fun.

[Munk]

heh, yeah. I've seen brass that had ZERO neck tension after firing. New bullet could be dropped in freely with no resistance.

As the others said, for making a dummy/snapcap; clean, resize, THEN add your bullet (after belling if necessary), and fill the primer pocket with silicone, hotglue or a combination of one of those and a spent primer.

[Sleighter]

Thanks everyone. We live and learn right? And for clarity, I'm reloading 9mm for a semi-auto.

[Chief-7700]

Each time the bullet hits the feed ramp it gets push back at bit. Multiple chambering of the same round will cause set back.

[xrMike]

^ Yeah, I've measured very slight setback on a round chambered several times in my 1911 with factory winchester ammo. It happens.