Ejection issues with M855 green tip gremlins

[Chris K]

Recently I built an upper to use as a "truck gun", really its just a GP plinker that can get used for anything 223 can do. I built it off of the following specs:

Rainier 14.5 match BBL 1:8 223 wylde chamber w/ Pinned and welded vortex flash hider
Rainier gas block
JD Machine Tech upper
BCM charging handle
Rainier BCG
ALG Defense modular hand guard (awesome kit if you haven't played with one)

It runs flawlessly with all factory 223 ammo I have fed it and my hand loads in various bullet/powder combos using .mil brass and shoots as good as the 4MOA dot in its vortex strikefire allows.

When I tried to run M855 green tip in it the brass sticks in the chamber. Failure to eject on the first round. It's not terribly stuck, a small brass rod easily taps it out with very little effort but its a bit of a bother for a gun that I might need "right now" for a pesky racoon or some critter I stumble acroos that needs shooting.

My first attempt to fix it was going to be a new extractor spring/o-ring to add a little tension to the rim of the cartridge, but from there it was going to be a call to Rainier to see whats up with either the chamber or the BCG.

Suggestions are welcome of course, any one had an issue like this with a carbine?

C_K

 

[newbmowner]

Does the Same lot of ammo work in other rifles fine? Do you happen to have a case gauge to check that the ammo is not out of spec? Probably a long shot but worth checking.

 

[07yzryder]

any markings on the ejected brass?
Any issues loading the rounds and ejecting the loaded round without firing?

is it LC m855 or factory reload m855?

 

[brcook03]

Possibly a slightly tight chamber but I would agree with the extractor upgrade that you have planned. I would also second running the ammo in other guns to see if the same issues show up.

 

[Thebelly]

I had the same issue, almost exactly: .223 Wylde from Rainier Arms, carbine gas system, FTE on M855. My fix was to break the rifle in. I shot some steel cased plinker stuff through it, and it has worked fine since then. I chalked that one up as 'the barrel/BCG combo had to wear themselves in'.

 

[hlee]

Polish the chamber.

 

[LRRPF52]

M855 is a hot load that will adhere the case to to the chamber wall with more pressure than most other loads. Combined with a longer, heavier bullet, it doesn't like to be pulled out of the chamber too early.

The extractor upgrade is treating a symptom, rather than the problem. How do you slow down the rearward movement of the carrier so that pressures subside enough to allow smoother extraction? Some solutions:

* Increase buffer weight, just like was done with the M4
* Increase recoil spring strength
* Increase carrier weight

The best answer for you is to find what works and will keep working with your other loads. Is this their stainless MLGS barrel, or do you have carbine length gas system?

 

[mtrmn]

Upgrade the extractor, turn down the gas a bit if the gas block is adjustable, add weight to the reciprocating mass.
My 16" carbines all have the semi-auto bolt carriers (lightweight) and work quite well with Wolff extra power springs and H2 buffers. YMMV

 

[Chris K]

Sorry I didnt ever get back in this thread, life got a little busy.

as for the questions;

-Same lot works in my Noveske perfectly, its true M855 so Im pretty sure its not the ammo.
-brass looks fine when it comes out minus a little nick in the rim where the extractor slipped its grip.

LRRPF52 -
Running a standard FA carrier, and an H Buffer. and yes, it is the mid length gas. I really don't plan on shooting M855 much, but like you said, its a problem that needs a soloution.

Thanks for the help guys.

C_K