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Posted: 9/23/2004 3:14:56 PM EDT
With the sunset of the AWB, I decided that it was time to build that AR pistol that I've always wanted.he

NOW the problems started!he) and install a carbine buffer tube, buffer, and spring. Cruising the board for answers to the problem, it seems like this is the way to go.

Anyone else having the same problems? It's not a mag problem because I've tried mags that run great in all of my other ARs. It seems that the pistol buffer keeps the bolt carrier from having enough inertia to reliably strip a round from the mag and then go into battery. The spring may also have too much energy to allow for complete return as well. I have the constant problem of the bolt catch failing to engage when running a mag dry.It's starting to piss me off enough that I may end up making a carbine outta the thing if I can't get it to work well. There's no room in my safe for an AR that doesn't work.
Link Posted: 9/23/2004 3:58:40 PM EDT
Been there, done that. Short barreled AR's are VERY finicky. Everything has to be just right, and will benefit from opening up the gas port just a LITTLE. But the first thing to do is make sure the chamber is polished perfectly smooth. If you have a chromed chamber use scotch-brite wrapped around an improvised drill bit and polish it as close to mirror finish as you can get without getting past the chrome, get rid of the tool marks. If you have a stainless or alloy bbl. use 400 grit wrapped around the scotch-brite to get a mirror finish. The polished chamber has usually solved all of my extraction problems. Another issue is the extractor pressure, you need to install a black or red extractor spring or "defender" type extractor stiffener, or you can use a small "O-ring" of appropriate size. Short barreld AR's cause extreme "extractor bounce" letting go of the round before it is out of the ejection port. Try the extractor fix and polish the chamber first, and I bet the problems will dissappear. Also check your mag alignment with the feed ramps, as long as it "dry cycles" the round into the chamber by using the charging handle, you should be o.k. If not, you may need to dremel your feed ramps, I.E. m4 type ramps. This is not very hard, just follow the countour of the current ramps and bring the ramp lower into the mag well, a little at a time. I have had to actually dremel into the upper receiver just a bit to compensate for mis-aligned parts. Just do a little at a time, until the rounds cycle reliably into the chamber without hitting and jamming up against the barrel extension.
Link Posted: 9/23/2004 4:26:29 PM EDT
Ah ha! I wondered if polishing the chamber would solve a few problems. I did have 2 rounds fail to extract from the chamber and wondered if a polish (or "extractor enhancement") might be in order.

Upon cleaning this evening, I discovered a very loose gas key. That sure would cause a whole bunch of problems! I staked the hell out of it with a cold chisel, dressed the cuts, and reassembled. I'll be at the range tomorrow morning so we'll see how it goes. I may be polishing a chamber tomorrow evening.

Never known an AR to be as finicky as these pistols. This is new to me.
Link Posted: 9/23/2004 4:55:50 PM EDT
I had the loose gas key on my kit also, I guess the don't torque the screws at the factory, just finger tight. The scotch brite is a good idea, but I advise against useing a drill bit, if you screw up you could ruin your rifleing. I sugjest useing a wooden dowl wich you can get at any hardware store, and you can make it long enough to use with the barrel on the upper.
Link Posted: 9/24/2004 12:48:17 PM EDT
Well, did ya get her going? Let us know.
Link Posted: 9/24/2004 6:16:20 PM EDT
Well, things are look'n up! Took her to the range today and had a good run. Funny how a loose gas key can really screw things up and bring the gremlins out to play. Went through 1 20-round mag and a 30 as well with no problems. However, I took an old aluminum cleaning rod and attached an old nylon 30 cal. brush to it. I then chucked it in a drill, wrapped a scotchbright pad around it, and commenced to polishing. I also used a patch soaked with JB followed up with a clean patch for polishing. I polished the hell out of that chamber until it shined like a mirror. Should work OK now but I'm gonna put a small O ring under the extractor just in case (pun not intended).

It'll be a day or two until I can get her to the range again but I have good feelings about things now. I may even start liking this pistol yet.
Link Posted: 9/24/2004 6:19:30 PM EDT
Good luck with your pistol build. Mine is acting up, so I have to check all those things. I suspect a bouncing bolt on my pistol (as I also have the long 10 or was it 11" barrel....)
Link Posted: 9/26/2004 1:25:34 PM EDT
I'm not sure about this "bolt bounce" thing. It seems like it would have to hit pretty hard for the bolt to return rotation and then back up a little. But it may be so.

What I really think is happening to these pistol buffers is that there's not enough energy in the bolt carrier to strip another round off of the mag and then go fully into battery. I think the bolt carrier gets more of a running start with regular buffer setups than with the pistol buffer. With the pistol buffer everything's compacted with regards to carrier movement. Just my thoughts..........probably way off as usual.

I'll be taking mine to the range sometime today to test her out again. The chamber has been polished and I've installed an O ring under the extractor. I've cleaned her up good and have mags loaded to go. I'll bet she'll run fine now.......................or at least I HOPE she does. If not, I may have to look more seriously at another buffer tube design.
Link Posted: 9/26/2004 3:21:43 PM EDT
OK. I digress. Bolt bounce is a real thing in this AR pistol. I just returned from the range where I tested it again. I had about a 20% failure rate of the bolt not being fully into battery. I heard and felt the bolt bounce several times.

Apparently this pistol buffer setup isn't going to work. Looks like I'll finally have to go the route of the shorty buffer design. I'm thinking about getting one, shaving the rails for the stock off of the bottom, and then sliding a ARFX foam sleeve over the tube. Anyone tried this? It seems like it'd look good and should make the pistol into a reliable weapon. Thoughts?
Link Posted: 9/26/2004 4:27:35 PM EDT
Yes woodsy, I did the exact thing you are talking about. I took the stock part off an old tele stock, cut as much of the square part off as I could with a band saw and then ground the rest with a bench grinder. A couple of the four holes(4 position stock) went fairly deep in the buffer tube so I filled them in with JB Weld and sanded them smooth. I sand blasted it and painted it with Brownell's gun coat and then stuck the piece of ACE foam on.

I think it looks pretty good.

If you pistol builders don't want to go this route, CMMG is building a new pistol buffer set up that is suppossed to work well and will be ready in about a week or so.
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