Tight chamber or what?

[woodnut]

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?

 

[acloco]

Polish the new chamber with Flitz or similar metal polish.

Use a cotton bore mop for the appropriate gauge of shot gun on a variable speed cord or cordless drill.

You will not remove any metal, but if a burr exists, this will help remove.


....and flush profusely with carb cleaner, then clean barrel as normal.

I would probably remove the barrel from the upper - be easier all the way around for you.

 

[J E Custom]

When chambering two identical chambers with the same reamer you must get the exact same head space. (Not easy, but doable) I am talking about to the ten thousandths or better.

If done correctly the ammo should fit both chambers as long as the ammo has been fired the exact
same amount (Brass will work harden and have more spring back the more it is shot and If one round of brass has been fired more times, even sizing with the same die and setting there is no guaranty it will be exactly the same size.

One other thing that could help is to fire form all brass in the tighter chamber and use the fire formed brass in the loose chamber.

J E CUSTOM

 

[woodnut]

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.As for using brass in Nell, I have a ton of it! Prairie dog shooting with an AR (suppressed!) is awesome!gun)

 

[acloco]

Would you break out the black sharpie for this thread please?

Blacken the neck/shoulder, entire shoulder, 1/4" down from the shoulder/body, and from 1/4" above the extractor groove of a fireformed case AND a fireformed and sized case.

Let the ink from the sharpie dry....and post a couple pictures after chambering the empty cases in the suspect chamber.

 

[woodnut]

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! Especially you, acloco. I did the sharpie and found what looked like only two small scratches longitudinally at the shoulder. Nothing more. But I decided to polish as it was a simple thing to do. Eureka! It worked!

 

[acloco]

This is great news.

Believe a Sharpie is on the short list of MUST HAVE tools on every reloaders bench.

 

[SidecarFlip]

Sharpie is nice, Dykem Machinist bluing is better. Come in a aersol can too.

 

[acloco]

SideCarFlip - very true. Little bit of cost and availability difference between the two though.


DieKem has it's place, but can be too thick sometimes - may not show minute issues. But, DEFINITELY can and should be used more often.

 

[SidecarFlip]

Thats all we use in the shop for layout and clearance checking. I always liked the blue but the newer red is nice and in a spray can, it's tops.

I still use the bottle and brush on but I'm old school and I like blue fingers...lol

Some of the new Sharpie fine line paint markers work nice as well. I've used the fine line red and green. I have a habit of reference marking assemblies for easier reassembly, ring sets included.

 

[acloco]

LOL! The blue fingers.....THAT is a true statement when using dyechem.

 

[woodnut]

Well, the mystery is solved. I talked with Redding and they believed I wasn't setting the die properly. Said I needed to "cam over". That means setting the die to contact the shell holder and then raise the ram and turn the die in some more so ALL the slack is taken out. Now I get good headspace and they are working perfectly! Thanks for you interest and advice.