Rim rip AR-15

[GOING FOR 2000]

I have a new upper for my AR-15. It is failing to eject, the extractor is ripping thru the rim. Tried using the bolt and carrier from my old upper, same thing. Tried both bolts and carriers in my old upper works fine.

Chamber looks fine no rough spots.

Any ideas would be appreciated.

 

[Sig685]

Re: Rim rip AR-15

It's the chamber.

I would bet that you are not using virgin brass.

The new chamber is tighter than the previous chambers and your brass is now too big for it. Use virgin brass or get a small base body die and pray.

If the brass is virgin (never been fired,) or this is factory ammo, you need to get the chamber inspected.

 

[Fritzcat]

Re: Rim rip AR-15

If you can chamber a round then manually eject the unfired round. Then your chamber finish is rough. You can take a strip of 400 emory cloth, fit it in your plastic cleaning rod end and use a drill motor to polish the chamber, but clean it and the barrel very good before trying. Are the primers very flat on the rounds fired?

 

[Hummer]

Re: Rim rip AR-15

Before you go polishing a chamber take a look at the cases and see if there are ridges running around fired cases. Also measure the diameter of your fired cases and diameter of you unfired cases.

Did you load this ammo? Did you check your sized cases in a L E Wilson case gage? You need to do this first. Read http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1367470#Post1367470

If this is a carbine type you may have a barrel with too big of a gas port. The first production run of M4s did this and they found the gas port size was the same as the 20" barrel. This being closer to the chamber than A2 length increased port pressure out the top and over drove the gas system. The second run of M4s had smaller gas ports and the problem went away.

Either way before I did anything I would contact the manufacturer and tell them what is happening because if you touch it you bought it.

Also you say it is failing to eject. Failing to extract is a chamber term, failing to eject means it has cleared the chamber and stays in the bolt way or is entrapped by the bolt coming forward. Failing to eject can be bad extractor / ejector spring.

Does the bolt come to the rear on last round and hold open? If not you have other problems.

check out http://www.superiorbarrels.com/ I have several of their barrels and no such problem. They have Wylde chambers.

 

[GOING FOR 2000]

Re: Rim rip AR-15

Std XM15e2 set up and 20" barrel.

The extractor rips thru the rim and leaves the case in the chamber. (Meant to say extract in earlier post)

Both function normally as far as ejection and hold open on last.

This problem can occur at any time, can be the first round, fifth, tenth, etc. then occurs every round after that. (pushes out easily with cleaning rod does not even feel stuck) This happens with, factory ammo, reloads (new and used brass Fed, Win, Rem, Mil-surplus.). Nothing odd with fired brass, rings, scars, etc and fired brass will chamber swap in both barrels though snug with a normal bolt drop and extract manually with a hard sharp pull.

Reloads-- Full length SB dies, trimed to length.

Both gas ports are the same size. Gas tube is clean and not binding. The only difference is the one barrel that works properly has a flash hider (irrelevant).

I have also swapped barrels between uppers, gas tubes gas keys, bolt carriers, bolts, replaced extractors on the upper receivers. nothing changes. I figure it has to be something with the chamber.

Both uppers were built with Mil.-spec parts kits, (no markings on upper receivers or barrels), the lower is Bushmaster. Both uppers group well at 100 yds. +/- 1.5" (iron sights)

I built this as something to play with as I am mainly a ELR bolt gun shooter and have very limited knowledge of gas guns. If there is a simple fix good, if not I will forget it, use the upper that works and just replace the other barrel later.

 

[Sig685]

Re: Rim rip AR-15

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 1000 YDS. IS FUN</div><div class="ubbcode-body">(snip)

I have also swapped barrels between uppers, gas tubes gas keys, bolt carriers, bolts, replaced extractors on the upper receivers. nothing changes. I figure it has to be something with the chamber.

(snip) </div></div>

You swapped barrels and the same upper was having the same problems?

 

[GOING FOR 2000]

Re: Rim rip AR-15

No.

No matter which upper or other components I use the barrel without the flash hider has the problem.

The barrel with the flash hider works fine.