My AR-15 wont work!-pix

bambambam

I've mentioned I'm piecing an AR-15 together.

I have it all, but handguard together. I took it to the farm today to shoot.

It will fire, remove the case half way & stick. I shot about 10 rounds pulling the rounds back and letting the bolt slam shut loading a new round. Still not cycling. So I took the Pmag out and loaded a single round. Still no eject with mag out.(This all steel case ammo)

I put 5-8 rounds of good brass cased ammo in the Pmag and tried to get it to cycle. With the brass ammo it would cycle back enought to eject about every 3rd shot but it never went back enough to load another round.

Is my gas block not lined up? Do I need to make the hole bigger on the gas block?(Tube has a good hole already)

This sucks..[:(]




62,
Look at the gas rings on the bolt, are the gaps aligned to allow too much gas to escape - they should be staggered to provide an effective seal.Could you elaborate on this some more? What do you mean by gas rings on bolt? Are these the washer stacked up in the middle of bolt? If so they look good.

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Should the BCG slide freely back/forth in the reciever? Mine is pinching about an inch back from chamber then frees up toward the back.

I think I may have bent the upper reciever clamping it in a vise when I put the barrel on!



I just put a box end wrench into the bottom of the upper reciever and twisted it with another wrench. It bowed the reciever out right near the dust cover. BCG slides back/worth freely now.

That's about enough to piss a guy off. Thought i ruined it.

Going back out to the farm to see if this puppy will rock n roll.

---

Well im at the farm, just shot it,damn thing still wont work. I did have a bunch of lube on the rings I noticed. Ill take it in the house and clean it out, try again.


It ejecting almost all shots now. Still not loading a new bullet and if it does getting a jam.[:(!] When i get home ill load some pix to see if it helps.

Here are some pix of the jammed rounds.


Round has come all the way back to get tossed.


I brought 2 mags the last time I shot to be sure it wasn't a mag problem. (all pmags)

Don McManus

With the brass handling better than the steel, have you thoroughly inspected the chamber for cleanliness, burrs, etc.?

I have an MCR-300 in 30-06 that when new would have a stuck casing every few magazines. Keeping it clean and very lightly oiled solved the problem.

62fuelie

On a home build it could be a variety of things or several small things ganging up on you. The first thing I would suspect is the strength of the recoil spring. I've seen some that could be used for suspension on a Cadillac. If you have a friend with a well-functioning AR compare yours to his, if possible at the range so you could try his in your rifle. The alignment of the gas block over the bleed hole should be checked, I wouldn't enlarge the hole. Check to be sure the gas block is fully tightened. Look at the gas rings on the bolt, are the gaps aligned to allow too much gas to escape - they should be staggered to provide an effective seal.

armilite

That is why you use the correct tool for the job. Vices and uppers is a no no that is why they use a receiver clamp and put that in the vice. To many people claim they can build AR's without special tools. If your receiver is indeed bent and you decide to replace it I'll loan you my upper receiver clamp.

Riomouse911

Sounds like you torqued the aluminum upper when you put the barrel in. If there is any hang up during the BCG travel caused by a bent upper, it will jam. I thought it might be grit/crap and underlubrication because it was a scratch build, so make sure all is spotless and blown out before it's lubed.

If you build another, change barrels, or do anything other than minor maintenance, I suggest buying the AR armorers blocks from Brownells. The upper receiver clamping block (A clamshell designed to fit over the receiver in a vise to prevent damage) and the lower receiver block (Looks like a solid plastic magazine that fits in the mag well) allows the gun to be clamped in a vise without damage. They're not too expensive and worth their weight in gold for just what you're doing.

The "gas rings" are the washers you describe. Over time they'll erode at the gaps causing too much blow-by and unreliability, and will need replacing at some point. When I clean these guns, if I have the 3 individual rings I stagger the openings. I was recently told in new AR armorer's courses they are saying that this isn't a big deal anymore, but I still do it out of habit. As an aside, I've gone to the one-piece gas ring set up from Brownells on all my AR's so this isn't an issue with mine anymore.

If the upper being bent isn't the issue, it could be misaligned gas ports, loose gas port block, crap in the ports or tube, pinched or bent tube, way too much lube on the bolt/gas rings inside the BCG (this caused an M-4 to jam repeatedly for a shooter this past month) and/or recoil spring/buffer alignment issues.

Let us know what the result is!

rufe-snow

quote:Originally posted by bambambam
Should the BCG slide freely back/forth in the reciever? Mine is pinching about an inch back from chamber then frees up toward the back.

I think I may have bent the upper reciever clamping it in a vise when I put the barrel on![:(!][:(!]



I just put a box end wrench into the bottom of the upper reciever and twisted it with another wrench. It bowed the reciever out right near the dust cover. BCG slides back/worth freely now.

That's about enough to piss a guy off. Thought i ruined it.[:D]

Going back out to the farm to see if this puppy will rock n roll[8D]



You might consider getting one of these receiver holding fixtures from Brownells. If you intend on building any more AR's in the future.

From my experience Brownells and Midway have all the tools you need for a home build. At least they did two years ago. God only knows if they have any in stock nowadays, with all the crazyness going on?

lts

what brand good brass cased ammo did you run? had similar situation with malaysian and african brass. was told to try pmc or federal and doing so cured the problem. guess mine is picky like a 22.

ogree

Check to see if your bolt carrier key is securely fastened.

bambambam

I have .057 on gas port hole. Saw on AR15.com they say it's supposed to be .068-.090.

I'm going to research this some more, I may be drilling this rip out.[V]

TRAP55

quote:Originally posted by ogree
Check to see if your bolt carrier key is securely fastened.

And check that the gas tube fits in the key nice and snug.

migrapilot

I had the same exact same problem yesterday with an AR I built for my daughter. I drilled the gas port a fraction larger and it now runs like a champ. It doesn't like pointed soft points, but that's a different issue. Make sure your barrel is not chrome lined. Drilling the hole could cause the lining to flake. Good luck.