I got a pistol AR not too long ago and have been haveing all sorts of problems. Now I know that this thing is not the most practical thing so I don't need a lecture on its practicality.
I already own EVERY conceavable AR configuration so I thought I would add this to my collection.

What it is doing:
1) will chamber a round but will not always fire. Hammer will drop but will only leave a small dent in primer. Same round when re- chambered will fire at another time.

2)Will sometimes double feed.

3) will fire a round and bolt will lock back if last round.

4)Will sometimes fire and chamber two in a row but never more than three without a problem

I bought it knowing about the problems, but figured it was mag issue but was wrong.

This is a kit upper on a PWA lower. I am useing new USGI mags w/ green follower. It is the type with the short buffer system that screws into the back of the lower. Not the bufferless type.


HELP:
I want to keep this thing and get it running

[url]http://www.ar15.com/forums/topic.html?b=3&f=66&t=176602[/url]

Thanks, I read the link and maybe it is my carrier or hammer???
Definetly not the gas since my bolt will lock back on last shot.

Any links or info on how to tweak the carrier and hammer. What tools do I use?

Thanks

If your getting binding at the hammer to disconnector, remove/grind .040 off the tail of the hammer were it is making contact with the back of the disconnector.

On the hammer is it's binding up on the firing pin during the forwards stroke, roll grind the top edge of the firing pin contact.

If you IM me an email address, I can send you a couple photos of what the end produce should look like.

[B]Quoted:

1) will chamber a round but will not always fire. Hammer will drop but will only leave a small dent in primer. Same round when re- chambered will fire at another time.[/B]

You need to check the barrel extension lugs, and the bolt lugs to make sure as the bolt enters the lugs cleanly without binding up on the sides.  
Also, make sure that the hammer is not binding up on the firing pin as the B/C return back to lock. The concept is to make sure that the bolt is fully locking up, and that something is not binding to prevent the bolt to fully chamber the round and lock.
One more thing is to check the firing pin protrusion.  It should be .030 to .039.  If you find that the protrusion is smaller than this, then you can thumb sand the back of the bolt to allow the firing pin to protrude the correct amount. (sand paper on your thumb as turn the bolt back and forth.  This allows the firing pin to go father into the bolt until the firing pin collar stops it’s forward travel).

[B]2)Will sometimes double feed.[/B]

If you mean two live rounds out of the mag, then the gas port may be a bit too large, and the carrier is coming back too fast, and the impact to the back of the receiver extension is causing the rounds to be danced out of the mag.  If the buffer uses a urethane end, then switch out the buffer to one of the softer buffer tech buffer ends to lessen the blow, or see if you can find a stronger recoil spring (the current one may be going south),

[B]3) will fire a round and bolt will lock back if last round. [/B]

This is good, but only if the carrier isn't coming back too fast, and causing the rounds to be danced out of the mag.

[B]4)Will sometimes fire and chamber two in a row but never more than three without a problem.[/B]

Is this due to the light primer strikes, feeding two rounds, or something else?

My buffer assembly is different than I have ever seen. It consists of a long pin that is attached to a disk kinda like a giant thumb tack. It fits into the buffer from the rear when the upper and lower are already attached.

A long spring slides over the staff or the pin (Or giat tack) and is held in the back of bolt carrier by a cylinder that slides into the rear of the carrier.

The whole buffer assemble is installed after the upper and lower is put together, not like a regular buffer system. there is also no need for the buffer retainer pin as the buffer never touches this pin.

Really when you think about it there is NO buffer, only a spring and a guide rod like on an auto pistol.

Is there a way to buy an actual buffer for this thing?

The light primer strike is usually the reason for stoppage, the double feed happens less often about 5 to 1

I can't thank you enough for all your help.

[B]Is there a way to buy an actual buffer for this thing?[/B]

Not as described.  But, By switching one mag/spring over to a Wolf extra power spring, this mag stand less of a chance of having the rounds danced out at carrier jar.

[B]The light primer strike is usually the reason for stoppage; the double feed happens less often about 5 to 1[/B]

Check the firing pin protrusion.
As long as the bolt is locking home, the only other item would be excessive headspace. Get your hands on a headspace gauge (no-go) and check the headspace of the chamber.

As for the buffer, for test purposes you could use a regular rifle tube and buffer/spring assembly. With your current setup the weight added to the carrier acts as a buffer by increasing the mass of the carrier thereby creating more inertia and resistance to movement under recoil, the spring is also very stiff.

Jeff

What weight added?
From what I can tell, this is a normal AR15 carrier. Am I missing something here?

All of the AR pistol recoil assmblies I have seen include a weight that inserts into the rear of the carrier and is drilled out for the recoil spring.

Go to Model 1 Sales web sight and you can find a pic of a typical AR pistol recoil assembly.

There may be different types out there that lack this but I would bet your pistol would behave a lot differently with it.

THis is form Model 1's site, does your setup look like this?

[img]http://www.model1sales.com/images/pistolbuf.gif[/img]

Jeff


EDITED to add that I just read back to one of your posts (duh on me) and what you describe apears to be the same, the carrier piece does add weight but is not exceddingly heavy. Carbon 15 pistols (and rifles for that matter) use a shorter carrier with a heavy weight.

You may want to purchase a new recoil spring, they are not the most robust when compared to a standard AR type.

OH thanks,
That is not a weight. It is a very light fitting that is there to hold the spring in place. It fits in the rear of the bolt carrier, and stops the spring from going in too far.

Doorkiciker,

See my edit, I'm a bit sloooowwwwww today ;^)

Jeff

P.S.

I have a Carbon 15 pistol and love it, they can be somewhat cantankerous at times but are much fun, they can also be extremely accurate.