Chamber too tight?

[wally247]

I have a new AR that I was shooting yesterday and I was having problems with my ammo. I didn't have any factory so I was shooting reloads, which I measured to be within SAAMI. Almost every round had a hard time chambering. I could force a round in with the forward assist and it would fire, some would eject and some would not.

I also took a marker to a few tight fitting rounds and there wasn't anything that looked strange after chambering.

What should I check or just chalk it up to break in? I only fired about 30 rounds.

All said and done I was pretty happy with how it grouped though. Best of the day with 20.5gr IMR 3031, 55gr V-Max.

 

[FLIGHT762]

How did you measure your reloads to be within SAAMI specs ?

Every time I've had a chambering problem with reloaded ammo, 98% of the time it was from NOT bumping (F/L sizing) the shoulders back enough.

Turn your F/L die in another 1/8th turn, F/L size a few cases and make some dummy rounds (no powder or primer) and see if they manually chamber and eject.

That might be your answer.

 

[243winxb]

Going in, like said by Flight762. For coming out, 20.5 gr of 3031 may be on the light/starting load side.

 

[rcmodel]

Adjust your sizing die as stated above.
You can chamber check sized brass.
You don't have to make Dummy Rounds out of it to see if it will chamber or not.

If it does you have a different problem after loading them.

Could be, you are crimping, either on purpose, or by accident.

And you could be imperceptibly buckling the shoulders.
That will lock an AR up tighter the the north end of a south bound gnat.

rc

 

[wally247]

Well I tried what you said Flight, it got a little better but still not good.

I'm going to pick up a box of factory ammo in the morning and see how that works.


243, 20 grains is min. 21.3 is max. So 20.5 is on the low end but it was the sweet spot out of the intervals I tried.

 

[wally247]

I should also add that a local shop built my AR, which made me think it could be a chamber/headspace issue.

This is not my first time loading .223 either, I had a different AR about a year ago that I successfully fired a few hundred reloads out of without a problem. But I'm not by any means a veteran reloader either.

 

[hartcreek]

I ran into this same problem with 30-06 25 years ago. I was using range pick up machine gun brass and had not full length sized.

 

[wally247]

Using RCBS small base dies.

But I figured it out. The chamber needed a good scrubbing. :banghead::banghead::banghead::banghead::banghead::banghead::banghead: I don't know why I didn't think of that right away. Cleaned it up with a copper brush and some solvent on a patch and it's much better now.

 

[spitballer]

This gets back to the age-old .223/5.56 interchageability issue, I think. I don't know if this helps but I have heard that the chamber is actually slightly looser or tighter depending on whether it is a .223 or a 5.56. I've always wondered why the 5.56 brass has to be so darned thick that it actually reduces capacity when it's surrounded by chamber anyway. Maybe a loose chamber compensates for this. Good luck.

 

[Crocboy]

Consider getting a Hornady Headspace Gauge. You can adjust your sizing die much more accurately using cases fired from your chamber to setback shoulders .002-.003". Your small base dies will size the cases plenty, in fact I think they size to .0005 smaller than spec. You are right that the issue is probably in the shoulder area and the Hornady Headspace Gauge is absolutely the best way to fix the chambering issue.