Tight chamber or what?

woodnut

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I have a wonderful pair of AR15s in 223A.I. Both barrels were chambered by the same reamer, but maybe not at the same time. Original fire-formed loads worked fine. But then reloaded , some would not feed and some would but not manually eject. The other AR has no problem.
So, I'm guessing there is a minute difference in the chambers. I have tried adjusting the sizer die in and out with no luck. I went from way off the shell holder to almost crush. No luck.
Measured brass and all reads good. I had thought I must have bumped the shoulder and created a bulge; but that has not appeared to be the case.
I am stumped! Has anyone else had this problem and what did you find to solve it?
 

MagnumManiac

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I have a wonderful pair of AR15s in 223A.I. Both barrels were chambered by the same reamer, but maybe not at the same time. Original fire-formed loads worked fine. But then reloaded , some would not feed and some would but not manually eject. The other AR has no problem.
So, I'm guessing there is a minute difference in the chambers. I have tried adjusting the sizer die in and out with no luck. I went from way off the shell holder to almost crush. No luck.
Measured brass and all reads good. I had thought I must have bumped the shoulder and created a bulge; but that has not appeared to be the case.
I am stumped! Has anyone else had this problem and what did you find to solve it?
OK, "almost crush" is not a term I'm familiar with, but bear with me.
Are you using the same die set for both rifles?
Do you set the FL die to touch the shellholder, then screw it IN 1/8-1/4 turn PAST TOUCHING THE SHELLHOLDER.
If you look at your press with a case in the die being sized, is there a gap between the shellholder and the bottom of the die? If there is, the case is NOT being sized to SAAMI minimum, which is most likely causing your issue.
The best solution is to keep your brass for each rifle separate, use 2 separare FL sizing dies and adjust accordingly.
It's been a while since I had a semi auto, but this is how I set mine up. Screw the die IN from touching the shellholder 1/32 turn increments, sizing, cleaning and chambering until a case chambers easily and extracts just as easy, any stickyness is a sign that more sizing is necessary.
Once you find the correct amount of sizing, lock the lock ring, I mark the lock ring and die, unscrew the die slightly and tighten the lock ring screw when the 2 marks align, then tighten the die back down.
Hope this gets you out of trouble.

Cheers.
lightbulb
 

BountyHunter

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Even chambered with the same reamer, there could be major differences in headspace between the two chambers just due to how the gunsmiths did the chamber and measured it.

Also, will strongly disagree with the recommendation to have the die touch the shellholder. That is the mftrs instructions and yes, it takes the brass back to SAAMI or even more, but routinely leads to excess headspace and brass separation as a result. Plus 3 times I have seen it push the shoulder back to the point it bulges out slightly at the edge causing non chambering. It is very hard to see if at all, but there will be a little ridge that can be felt with a metal straight edge. That is often hard to diagnose because people follow the mftrs instructions and think that something else is wrong. You can check by taking a piece of fired brass, back the die off .020 and sizing down until it chambers if that is the problem.

Bolt guns should be set up to have about .001-.002 pushback and semis most run it to .003. Depending on the chamber you might have to use a small base die in autos.

Read this how to do it properly.
http://www.longrangehunting.com/forums/f28/how-set-up-fl-sizing-dies-one-masters-game-153072/

If you have the tools to accurately measure headspace and find the two guns are different you can buy a set of "Skip Otto Die Shims) about $15 and set the die up for the shortest headspace and then just use the appropriate shim under the die for the next gun. That way you can use one die set for multiple guns with accurate headspace for each.

It is not uncommon for the die to be too long and about .020 have to be ground off as they ran the reamer in too deep.

You also might have a burr in the chamber of the one so check that out as you have run the headspacing in and out. Sounds like a defect in the chamber of some kind.
 

J E Custom

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Even chambered with the same reamer, there could be major differences in headspace between the two chambers just due to how the gunsmiths did the chamber and measured it.

Also, will strongly disagree with the recommendation to have the die touch the shellholder. That is the mftrs instructions and yes, it takes the brass back to SAAMI or even more, but routinely leads to excess headspace and brass separation as a result. Plus 3 times I have seen it push the shoulder back to the point it bulges out slightly at the edge causing non chambering. It is very hard to see if at all, but there will be a little ridge that can be felt with a metal straight edge. That is often hard to diagnose because people follow the mftrs instructions and think that something else is wrong. You can check by taking a piece of fired brass, back the die off .020 and sizing down until it chambers if that is the problem.

Bolt guns should be set up to have about .001-.002 pushback and semis most run it to .003. Depending on the chamber you might have to use a small base die in autos.

Read this how to do it properly.
http://www.longrangehunting.com/forums/f28/how-set-up-fl-sizing-dies-one-masters-game-153072/

If you have the tools to accurately measure headspace and find the two guns are different you can buy a set of "Skip Otto Die Shims) about $15 and set the die up for the shortest headspace and then just use the appropriate shim under the die for the next gun. That way you can use one die set for multiple guns with accurate headspace for each.

It is not uncommon for the die to be too long and about .020 have to be ground off as they ran the reamer in too deep.

You also might have a burr in the chamber of the one so check that out as you have run the headspacing in and out. Sounds like a defect in the chamber of some kind.

+1 What BH said.

There are some additional comments on your other post in the gun smithing section.

J E CUSTOM
 

woodnut

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Thanks guys, I appreciate your answers. I have been reading your posts, thinking, and now believe the easiest (and maybe the best?) direction is to shoot some brass to fireform in Wanda. Then take accurate measurements and compare to those that don't fit and pray I can find something. I do agree with J E Custom, touching the shell holder with the die is not a good thing. It may have started the problem,too. Wish me good luck as the other solutions may be very difficult to do. Oh, and right now I'm going to cut the mouths of a couple just to see if the chamber is a teeny bit short. Probably not, but an easy task and will eliminate/find that.
 

woodnut

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YEE HAA! You may not believe it, but a very good swabbing of JB and Flitz showed that the chamber was in need of polishing! Do not know why, but it was very dirty and now the cases run though it like they should . Hard to believe that would cause such a problem, but apparently it did. I thought I was good at cleaning,too. But, that chamber is now smooth and clean and running properly. Whew!Thanks for all your good advise!
 

woodnut

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Guess what? That really didn't solve my problem. Sooo, I've had a good gunsmith use his eyes and after head scratching, run a reamer ever so lightly and took out maybe .001. First, we took a case and turned the rim off about .001 and it ran like it should. Went to the range, shot some that wouldn't eject, and they shot, ejected fine. Thought I was home free. Nope.
So, I ran a mike on two pieces of brass. took seven measurements and can't see but one that possibly could be the culprit. The web area. It's only a little diferent, but that could make it tight enough to stick. The good says .3765 and the bad says .3775. That ain't much.
So, if I have my sizer body shortened, will that size the web area more? Right now the die is making full contact with the shell holder and both cases came from it. Again, I can't figure it out. Oh, and there are two brands of brass, L.C. is good and Lapua isn't. Just two case though.
I guess if I can chamber them, which they do, firing will eject them. If a live round sticks, I could either pound the ground and eject or just shoot it out. But I want sized brass to run in and out smoothly! In all my long life, I have NEVER had this un-explained problem.
Could it be that sticking empty brass and letting the bolt slam foreword it sometimes "pinches" the brass ? Still, I can't find any measurements to suggest this. I could just be "crying over spilled milk" and need to just load and shoot! But I think not.
 

MagnumManiac

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Just buy yourself a 'Samall Base' sizing die and keep your brass separate for each rifle.

Cheers.
lightbulb
 

rcoody

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woodnut

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Thank you for that info. I use Reddings now. Guess I'll have to bite the expensive bullet and get a custom die from them. Seems to be the (hopefully!) answer. The only measurement I could find that could possibly be the culprit was in the web area. Odd though, you usually don't size the web, just ahead of it. That seems to be good. I know it may only take a tiny bit of tightness to stick so it still could be it. Thanks again!
 

rcoody

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Thank you for that info. I use Reddings now. Guess I'll have to bite the expensive bullet and get a custom die from them. Seems to be the (hopefully!) answer. The only measurement I could find that could possibly be the culprit was in the web area. Odd though, you usually don't size the web, just ahead of it. That seems to be good. I know it may only take a tiny bit of tightness to stick so it still could be it. Thanks again!


if you are going to the trouble and expense of making custom dies you may want to send in a cast of your chamber to redding. Here is a link about how to do it.

http://bulletin.accurateshooter.com/2014/04/tech-tip-how-to-cast-your-chamber-using-cerrosafe/
 

woodnut

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Actually, I have now been in touch with Redding and sent them, at their request, several fired cases and the die. They will scrutinize all and give me a verdict. Will let you know in a short while.
I also went shooting Sat. and even when a case couldn't be pulled out in a normal fashion, it did go home and did fire and did eject. Accuracy was on par. Can hardly wait to hear from Redding!
 
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