Barnaul 5.56 in LM4

**Rommel** · 24-06-2021, 14:59

Hi Guys
I recently bought a few boxes of Barnaul Steel cased 5.56 for my LM4, now, they run well, but I noticed every few cases have a cracked neck. Is this ok, or will it stuff up my chamber or worse???

**FNBROWNING** · 24-06-2021, 15:06

Not ok. It will damage your chamber over time.

**A-R** · 24-06-2021, 18:31

Theoretically, cracked necks are supposed to erode the chamber at the spot where the crack sits.

If the case still seals in the chamber after getting cracked, there is no gas escaping, so the erosion will be very limited.
If the crack allows hot gas to escape rearwards, between the case and chamber, then the erosion will be more severe and should be avoided.

So try to determine if the cracked cases still seal the pressurized gas in the chamber, or if they allow pressurized gas to escape rearwards. That will be the determining factor.

**Fire-stick** · 24-06-2021, 19:11

I would gather that these are new factory cases being fired and not any reload of sorts?
It sounds like there is possibly a bad batch with the neck splits occurring unless I am on a different chapter and reading something else?

**CorditeCrazy** · 24-06-2021, 20:11

Originally Posted by Rommel

Hi Guys
I recently bought a few boxes of Barnaul Steel cased 5.56 for my LM4, now, they run well, but I noticed every few cases have a cracked neck. Is this ok, or will it stuff up my chamber or worse???

May I ask, where did you get?

**tobie** · 24-06-2021, 21:46

I'm sure someone will chirp in, but I believe that the R/LM series are chamber chromed, so I don't think it will have any real effect on the chamber/throat.

**FNBROWNING** · 24-06-2021, 22:17

Originally Posted by tobie

I'm sure someone will chirp in, but I believe that the R/LM series are chamber chromed, so I don't think it will have any real effect on the chamber/throat.

A cutting torch cuts through chrome just the same. The coating is quite thin in the chamber.

**Rommel** · 25-06-2021, 08:17

Hi, got them at Rosenthal in Windhoek...

**Rommel** · 25-06-2021, 08:19

Hi, they are new Factory ammo... I shoot them from my .223 Saiga aswell, and they do not crack in this rifle, only in my LM...

**Gleock** · 25-06-2021, 09:39

Originally Posted by FNBROWNING

A cutting torch cuts through chrome just the same. The coating is quite thin in the chamber.

Oxy-Acetylene runs about double the temp of gun powder.
The hottest powers burn slightly under the melting point of chrome.
Not saying there won't be damage, but its unlikely anyone is shooting enough to damage a chrome limned chamber, especially if they are shooting factory ammo.