Potentially over-gassed AR

agabriel said:
The old buffer shaked around. The new one does not.
Click to expand...


Yeah, I had a feeling that would be the case. You have a cheap-ass buffer, get a non-cheap-ass buffer and things should be good.
 
The dead blow aspect of the recoil buffer started working today after a lot of ammo; verified while cleaning. It started to lock back after the last round most of the time.

The rifle still seems a little over gassed since it isn't constantly locking back and where it throws brass (3 o'clock).

Anyway, I'm going to see what the sales look like in a few days and order a replacement. I feel like I have a much better handle on what is needed.
 
agabriel said:
I found and posted a graphic (earlier in the thread) that shows how to tell based on ejection pattern. The graphic isn't mine and was found through a lot of searching. This was thread where I found it:
https://www.okshooters.com/showthread.php?160495-AR-15-Buffer-weights

Anthony
Click to expand...


There are a bunch of reasons why brass lands where is does. Ejectors, extractors, lube, etc. Over gassed can land at 4 o'clock too, Depends on how bad its over gassed, gas system etc. At some point it is better to get a correctly drilled gas port than to keep adding buffer weights
 
Supermoto said:
The Bolt tries to unlock before the chamber pressure has dropped, so the case sticks to the chamber wall, slowing down the bcg speed.
Click to expand...

okay but if the rifle worked fine with the original buffer, tube, and spring, then I don't think that's what's happening here. It seems like the gas system worked fine and the only thing that changed with the buffer, tube and spring.

I was also thinking it's short cycling and not over gassed. Where the brass lands, and how far it goes, can sometimes be an indicator--far forward could be over gassed and short distance to the rear would be more under--but it's not an exact science.

The other thing I would do, just because it's so easy, is with the rifle unloaded, close the bolt then insert an empty mag and pull back the bolt and release it--does it lock back?

Did the OP put grease or something in the buffer tube? You shouldn't put anything in there--although some makers will put in a tiny bit of grease. Looking at what you got on Amazon there are some bad reviews. Some say the buffer is a sloppy fit in the tube and i wonder if that would slow down the cycle and cause short cycling? But do try a friend's buffer and/or carbine spring to see if it makes a difference.

FWIW, I never buy gun parts from Amazon or no-name brands. The LMT tube, spring, and buffer is like $60, which is twice as much but really just $30 more--and that's for a top notch brand. Back when I took the Armalite armorer course they warned us about cheaply made buffers full of solid lead, shotgun pellets, or misc trash. The buffer should rattle and have three cylinders floating inside it, like these:

buffer-construction.jpg
 
Last edited:
Another_David said:
okay but if the rifle worked fine with the original buffer, tube, and spring, then I don't think that's what's happening here. It seems like the gas system worked fine and the only thing that changed with the buffer, tube and spring.

I was also thinking it's short cycling and not over gassed. Where the brass lands, and how far it goes, can sometimes be an indicator--far forward could be over gassed and short distance to the rear would be more under--but it's not an exact science.

The other thing I would do, just because it's so easy, is with the rifle unloaded, close the bolt then insert an empty mag and pull back the bolt and release it--does it lock back?

Did the OP put grease or something in the buffer tube? You shouldn't put anything in there--although some makers will put in a tiny bit of grease. Looking at what you got on Amazon there are some bad reviews. Some say the buffer is a sloppy fit in the tube and i wonder if that would slow down the cycle and cause short cycling? But do try a friend's buffer and/or carbine spring to see if it makes a difference.

FWIW, I never buy gun parts from Amazon or no-name brands. The LMT tube, spring, and buffer is like $60, which is twice as much but really just $30 more--and that's for a top notch brand. Back when I took the Armalite armorer course they warned us about cheaply made buffers full of solid lead, shotgun pellets, or misc trash. The buffer should rattle and have three cylinders floating inside it, like these:
Click to expand...

My comments weren't about fixing his rifle, just about diagnosing an overgassed gun. For his specific gun, I agree with you...crap parts
 
a bolt that will not lock back is indicative of an issue with the gas system. Load 5-10 magazines with 1 round each, fire them all, if the bolts not locking back start with the easy stiff first. check the gas key on the bolt, check the front sight block, put a carbine suffer in the gun. Check the gas rings on the bolt. My guess is the buffers to heavy or you have a gas leak, whats the condition of the gas tube? is the gas tube out of line with the gas key? are you running a carbine length spring in the rifle?
 
Another_David said:
okay but if the rifle worked fine with the original buffer, tube, and spring, then I don't think that's what's happening here. It seems like the gas system worked fine and the only thing that changed with the buffer, tube and spring.

I was also thinking it's short cycling and not over gassed. Where the brass lands, and how far it goes, can sometimes be an indicator--far forward could be over gassed and short distance to the rear would be more under--but it's not an exact science.

The other thing I would do, just because it's so easy, is with the rifle unloaded, close the bolt then insert an empty mag and pull back the bolt and release it--does it lock back?

Did the OP put grease or something in the buffer tube? You shouldn't put anything in there--although some makers will put in a tiny bit of grease. Looking at what you got on Amazon there are some bad reviews. Some say the buffer is a sloppy fit in the tube and i wonder if that would slow down the cycle and cause short cycling? But do try a friend's buffer and/or carbine spring to see if it makes a difference.

FWIW, I never buy gun parts from Amazon or no-name brands. The LMT tube, spring, and buffer is like $60, which is twice as much but really just $30 more--and that's for a top notch brand. Back when I took the Armalite armorer course they warned us about cheaply made buffers full of solid lead, shotgun pellets, or misc trash. The buffer should rattle and have three cylinders floating inside it
Click to expand...

The buffer started rattling yesterday and the rifle started locking back ~70% of the time. I also agree - the rifle ran great pre-upgrade. I think it the recoil buffer is probably just on the edge and an H or an H2 buffer will make it reliable. I'm wondering in the bolt carrier is part of the reason it needs a slightly heavier recoil buffer. The recoil buffer does not have a full profile.
 
The reason for heavy buffers was to help slow the bolt from unlocking before the gas pressure had subsided, so that the extractor would be able to maintain its grip on the cartridge rim during the extraction cycle, Heavier buffers and stronger extractor springs with O-rings etc where all to help with the extraction and ejection on the M-4.
 

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