AR Rim Ripping Help

[baltimorelaw]

Bought a short barreled upper (10.5" barrel + 5.5" fixed FH) and it rips the rim on the brass (but doesnt completely rip it off). I presume this is from too much gas, dirty/rough chamber and/or too weak of a buffer. Has anyone else had this issue and how did you solve it?

I was thinking about getting a heavy buffer assembly to slow down the bolt cycling speed giving the brass a little more time to stop sticking to the walls of the chamber after initial expansion. If you have any thoughts please share!

 

[clandestine]

Get a M16 Bolt Carrier (If you Dont Have one)

Get a Colt 9mm Buffer

Get a New Colt Buffer Spring

Are you sure the bolt is locking up correctly/Headspace too tight, or too loose?



Is the Chamber Chrome Lined? The AR really should be run with a Chrome lined Chamber

Who drilled the Gas Port, or assembled th upper? It could be drilled too large (Gas Port)for that upper to function correctly.

If the Chamber is not chrome lined then the chamber can be polished

 

[baltimorelaw]

Get a M16 Bolt Carrier (If you Dont Have one)

Get a Colt 9mm Buffer

Get a New Colt Buffer Spring

Are you sure the bolt is locking up correctly/Headspace too tight, or too loose?



Is the Chamber Chrome Lined? The AR really should be run with a Chrome lined Chamber

Who drilled the Gas Port, or assembled th upper? It could be drilled too large (Gas Port)for that upper to function correctly.

If the Chamber is not chrome lined then the chamber can be polished

I have to check the headspace but I believe its OK. Waiting on a set of go/no-go gauges to confirm. Not sure if the chamber is chrome lined. I will try cleaning/polishing it good to see if that makes any difference. I am assuming a chrome lined chamber would reduce sticking? The upper was sold to me as a YHM upper but I am not 100% sure the guy was truthful I have to pull it apart and ID the markings to see who made it... It looks identical to the BM model with the same length barrel and FH.

Why the 9mm buffer instead of a heavy buffer assembly? Also, what issue could the BCG be causing?

 

[clandestine]

I have to check the headspace but I believe its OK. Waiting on a set of go/no-go gauges to confirm. Not sure if the chamber is chrome lined. I will try cleaning/polishing it good to see if that makes any difference. I am assuming a chrome lined chamber would reduce sticking? The upper was sold to me as a YHM upper but I am not 100% sure the guy was truthful I have to pull it apart and ID the markings to see who made it... It looks identical to the BM model with the same length barrel and FH.

Why the 9mm buffer instead of a heavy buffer assembly? Also, what issue could the BCG be causing?

The Semi AR BGC is lighter than a M16 BCG. The M16 BCG since its heavy will cause the gun to stay locked up longer.

I have never experienced any problem with YHM Uppers. I am doubtful that its really a YHM Upper, and I dont recall YHM marking their Barrels or Uppers so disassembly for that reason may be a waste.

Unless you have the right tools to polish and gauge the chamber I wouldnt do it yourself. If you go too far then you can open up the headspace and cause the gun to expolde when its fired.

You are correct about the chrome lined chambers. They are slicker and dont let the brass and any carbon stick as easily as a non-lined chamber.


BTW are these problems with brass cased ammo, or steel cased ammo.

Also what is the gun chambered for 5.56 or .223 (there is a difference BTW). If you have a .223 chamber and try to shoot 5.56 you will see what you are experiencing with a new gun (Not broken in)

The 9mm buffer is heavier (From my memory at least), than the Heavy Buffer (H2). The 9mm Buffer fixes problems better for guns that I service than the H2 does.

 

[JeepDriver]

You need to delay extraction and allow the chamber pressure to lower.

A h2 buffer and a flat wire Chrome silicon spring should cure most of the problems.

 

[CorpsmanUp]

Wow.

Had this happen at the range today.

Fired about 400 rounds through this gun. Decided to take some Wolf ammo out. Fired about 15 rounds and one got stuck about 3/4 in the chamber. The extractor ripped off a perfectly shaped chunk out. Had to pop it out with a rod.

Not going to be using Wolf anymore.

 

[clandestine]

Wow.

Had this happen at the range today.

Fired about 400 rounds through this gun. Decided to take some Wolf ammo out. Fired about 15 rounds and one got stuck about 3/4 in the chamber. The extractor ripped off a perfectly shaped chunk out. Had to pop it out with a rod.

Not going to be using Wolf anymore.

Wolf isnt great ammo, but if an AR wont shoot it then IMHO theres a problem with that AR.

I dont shoot a heavy amount of Wolf through my AR's but I have made them all work on Wolf, and sustained sessions of it too.

All of my firearms are serious use systems, and I might not have the luxury fo obtaining premium ammo one day when I need ammo.

Just my opinion on the subject. YMMV

 

[CorpsmanUp]

Wolf isnt great ammo, but if an AR wont shoot it then IMHO theres a problem with that AR.

I dont shoot a heavy amount of Wolf through my AR's but I have made them all work on Wolf, and sustained sessions of it too.

All of my firearms are serious use systems, and I might not have the luxury fo obtaining premium ammo one day when I need ammo.

Just my opinion on the subject. YMMV

I've actually been thinking the same thing.

I've been researching what makes this happen. I'm going to fire a few hundred rounds of non laquered stuff and see what happens

Wolf isn't that much cheaper for me to worry about it.

 

[clandestine]

I've actually been thinking the same thing.

I've been researching what makes this happen. I'm going to fire a few hundred rounds of non laquered stuff and see what happens

Wolf isn't that much cheaper for me to worry about it.

It usually dosent take much to make it work with Wolf.


Im sure you will figure the cause out.

 

[baltimorelaw]

The Semi AR BGC is lighter than a M16 BCG. The M16 BCG since its heavy will cause the gun to stay locked up longer.

I have never experienced any problem with YHM Uppers. I am doubtful that its really a YHM Upper, and I dont recall YHM marking their Barrels or Uppers so disassembly for that reason may be a waste.

Unless you have the right tools to polish and gauge the chamber I wouldnt do it yourself. If you go too far then you can open up the headspace and cause the gun to expolde when its fired.

You are correct about the chrome lined chambers. They are slicker and dont let the brass and any carbon stick as easily as a non-lined chamber.


BTW are these problems with brass cased ammo, or steel cased ammo.

Also what is the gun chambered for 5.56 or .223 (there is a difference BTW). If you have a .223 chamber and try to shoot 5.56 you will see what you are experiencing with a new gun (Not broken in)

The 9mm buffer is heavier (From my memory at least), than the Heavy Buffer (H2). The 9mm Buffer fixes problems better for guns that I service than the H2 does.

It's chambered for 5.56 and I'm shooting 223 in it so it should be fine in that respect. It might actually be a YHM then becuase it has no markings that I could locate. It looks identical to an upper that BM sells (see attached pic), but I have a BM and it is clearly marked so I would think that if this were one it would be marked too.

I'm surprised the 9mm buffer is heavier than the 223 buffers. Wasn't expecting that. I am going to switch lowers to see if the problem still occurs when its on my other lower. If it does, its getting a chamber polish and a buffer and spring, and if it still does it, then I'll look into an M16 BCG.

Thanks for all the info.

 

[smokey]

I've actually been thinking the same thing.

I've been researching what makes this happen. I'm going to fire a few hundred rounds of non laquered stuff and see what happens

Wolf isn't that much cheaper for me to worry about it.

http://www.theboxotruth.com/docs/edu18.htm

seems to be the steel cases don't expand as much and allow some carbon blow-by to build up in the chamber. If you go from steel to brass(which expands more), often the brass will cling on to the carbon and have a rough extraction. If you just pass a chamber brush over it a little and remove some of the carbon, it's nothing to worry about. My ar build with a del-ton chrome-lined upper had one fail to extract the first time i brought it out, but after that has run perfectly with wolf.

 

[CorpsmanUp]

http://www.theboxotruth.com/docs/edu18.htm

seems to be the steel cases don't expand as much and allow some carbon blow-by to build up in the chamber. If you go from steel to brass(which expands more), often the brass will cling on to the carbon and have a rough extraction. If you just pass a chamber brush over it a little and remove some of the carbon, it's nothing to worry about. My ar build with a del-ton chrome-lined upper had one fail to extract the first time i brought it out, but after that has run perfectly with wolf.

I've read that too.

Previous to the failure I shot about 100 rds of PMC/PRVI. It was pretty hot temperature wise. I then shot a 20 rd mag of 55gr Wolf - no problems.

The failure to eject came at the 5th rd of 62gr Wolf.

There are various reasons why this occurred. From what I read it could be anything from underpowered rounds to a perfect storm of events i.e. ambient temp, how long the rd was cooking in the chamber, carbon buildup, etc.

It's not necessarily a 'problem with the weapon.'

Going to shoot a few hundred rounds of non Wolf ammo Sunday and see what happens.

 

[CorpsmanUp]

Well, shot another 300+ rounds on Sunday.

No problems whatsoever.

Heads up on some good stuff for cleaning your gear:

http://www.midwayusa.com/viewproduct/?productnumber=784639

This stuff makes baby Jesus happy...