Anyone seen this? (ar-15 problem)

[TonyAngel]

5:00 ejection sounds like it's might be right on the edge of being under gassed. Why don't you just go back to the standard AR15 bolt carrier.

How did you check the gas system? If your system is bleeding gas off someplace, I'd check the gas rings. I've had gas rings wear out in as little as 500 rounds.

Just don't go monkeying around, like taking weights out of the buffer, trying to cure a symptom. Find the problem. Although I suggested going back to the lighter carrier, your rifle should run with the M16 carrier as well. My guess is that you're bleeding gas someplace.

Without having the rifle in my hands it's hard to say where the leak is. It could be a bad seal between the barrel and block, block and gas tube, gas tube and gas key, gas rings or a combination of all.

 

[HKGuns]

What changed is the first question you should ask yourself.....Put the original BCG in and see if you still have the problem.

 

[madcratebuilder]

What changed is the first question you should ask yourself.....Put the original BCG in and see if you still have the problem.

+1

Try the original BCG you had in the rifle. Is the new gas block port matched to the barrel gas port perfectly?

 

[kaferhaus]

It's either gas rings or the buffer/spring.

 

[Al Thompson]

I'm with kaferhaus on the recoil spring and buffer.

carbine length gas system, (snip) with a standard a2 buffer spring and buffer. (magpul PRS)

Seems to me that if you are running an A2 buffer and recoil spring with a carbine length gas system, you'd be "undersprung". I'm no expert, but I think that would display the same symptoms as undergassed.

 

[Mot45acp]

When you put the gas block on, did you account for the space where the former handgaurd end cap rested? The small area between the shelf on the barrel and the rear of the gas block.

The gas block might be a hair too far back.

 

[d2wing]

I had that issue before I switched to a heavier buffer to slow down the BCG. It is ejecting ok?

 

[nmxdaven]

The gas block, origonaly a hex screw on, was milled out to accept pins, so the gas block should be spot on. Ive done it a few times before with other rifles, and never had any probems. I checked it again yesterday (Pulled out the pins and checked the allignment, and it seemed perfect.

I dont particuarly want to go back to the standard carrier, as its pretty crappy. If I could get it running with this one I would be much happier. (and save a bit of money) But next time I go out I will try it with the origonal and see if that clears up my issues.

A m-16 carrier/rifle buffer should be working fine with a carbine gas system now that I think things through. Carbines run so gas heavy I shoudnt be having these issues at all. I was just VERY carfull about getting the gas system alligned correctly, so if it is a gas problem I would think it indeed might be the rings.

Al Thompson: Can you explain "undersprung" in a little more detail to me? I would think If anything I would be oversprung with the extra gas pressure compared to a rifle length, but I've never run diffrent gas systems with diffrent buffer systems before, so this is all new to me.

 

[Al Thompson]

As I understand it (and I might be all wet), the carbine used a heavier buffer to add momentum to slow the cycle down. I'm thinking that with the A2 set up, you may be seeing the action cycle faster.

I've got a few minutes, let's see what I can find...

Edit:

Take a look at the first post (Mr. Roberts's post) and see what you think. I like to try the cheap solutions first.

http://www.thehighroad.org/showthread.php?t=199626

 

[Jeff White]

I suppose that it's possible, but I have never seen bolt bounce (too much gas causing the bolt to move faster then the spring in the magazine can feed the rounds) in a semi auto before. I have seen it in full autos, which is why the heavier buffers were developed for the M4A1.

I'm leaning towards a gas problem somewhere in the system. The fact that it ran fine until you changed it over eliminates the magazine issue in my mind.

 

[Bartholomew Roberts]

I think I would try working backwards from what you changed starting with the BCG. That will at least tell you where the problem is. My guess is gas key or gas rings on the new BCG. Have you tried extending the bolt and standing the BCG up on the bolt face? If the gas rings are good, the bolt should not collapse at all.