Bullet creep when chambering.

[popper]

Did you size new brass before loading? I just use the Lee die set, no problem.

[savage204]

Did you size new brass before loading? I just use the Lee die set, no problem.

Yes, i ran them through a Hornady FL die with and without the expander ball installed.

[dellet]

Since it’s new brass, did you clean the inside of the necks? Possibly left over lube, Q-tip and alchohal or acetone, something without an oil additive.

Knowing what spring and buffer you have might also be a clue. The system was designed around pushing a cartridge with a bullet half the weight, that was crimped into a canalure. Too much weight or an extra power spring can add to the problem.

The other thing to check is to make sure that you are not also crushing the shoulder of the brass. If it is slamming into the chamber hard enough to un-seat the bullet, it’s likely hitting hard enough to push the shoulder back. Accuracy will suffer.

Just some other things to check.

[savage204]

After sizing i cleaned inside the case neck with a brass brush. Then sprayed the inside and outside with brake clean, just happen to be what was close at hand.

Good point on the spring and buffer. To be honest i don't know the weight of the buffer off hand, i'll check when i get home this evening. I'm almost positive it's standard carbine buffer but will double check. Is a lighter buffer the way to go for the 300 blackout?

I was tossing the idea around of getting a sheridan gauge, looks like i'll be adding that to the list as well.

[bentstick]

Sages is a good source,have bought there quite a bit in the last 5 months never disappointed, cheers!!

[savage204]

Since it’s new brass, did you clean the inside of the necks? Possibly left over lube, Q-tip and alchohal or acetone, something without an oil additive.

Knowing what spring and buffer you have might also be a clue. The system was designed around pushing a cartridge with a bullet half the weight, that was crimped into a canalure. Too much weight or an extra power spring can add to the problem.

The other thing to check is to make sure that you are not also crushing the shoulder of the brass. If it is slamming into the chamber hard enough to un-seat the bullet, it’s likely hitting hard enough to push the shoulder back. Accuracy will suffer.

Just some other things to check.

Finally got the Lee collet die in and was able to get to the reloading bench some this morning.

The buffer is 4.3oz, the spring is the one that came with the SB brace.

The collet die defiantly helps with neck consistency. Measuring the inside of the neck before using the die I was getting .304-.306 in some cases. After using the die I was getting .305 consistently. It did seem to help some as far as the creep goes. After chambering a dummy round four times I had a c.o.a.l growth of .010, before I was getting that on the first chambering.

I did measure the headspace with a Hornady headspace comparator. After FL sizing I am getting 1.068, after chambering once it measures 1.067 and stays at that length until the fourth chambering and I got a 1.0665. So it seems like the case is hitting the shoulder when chambering. Could the chamber be cut short? I tried to turn the FL die down a little to get the shoulder back some but 1.068 is all I could get out of it. My press is a lee classic so there isn't much cam over on it.

Here is the measurements at each chambering.
Starting- 2.060
1- 2.066
2- 2.067
3- 2.068
4- 2.070
Is this acceptable?

[bangbangping]

So it seems like the case is hitting the shoulder when chambering.

Yes. The shoulder is what stops the forward motion of the case. Measure a fired case. I'd wager it's longer than 1.068". No need to set your die down further.

[popper]

That would be an h3 buffer, standard spring? My Lee die plug is 305 and works for cast or Jax.

[savage204]

I'll fire a few factory rounds in the next day or so and measure those. I'll post the results.

According to my Google search 4.3oz is slightly lighter than a H2 buffer.

[savage204]

Measure a fired case. I'd wager it's longer than 1.068". No need to set your die down further.

There wasn't a lot of day light when I got home but I did shoot three factory rounds ( two Armscor and one Hornady) so I could measure the shoulders and at least get an idea. All three measured 1.080. So this tells me the case shoulders are not hitting the chamber with my sized cases measuring 1.068.

So now I'm even more confused. I can borrow a standard weight carbine buffer and try that. When I get paid this week I'll order some converted LC brass as was suggested also.

I'm kinda lost at this point. I thought maybe I would pull some of the 147gr Armscore bullets and load those just to see if it made any difference.