I built a new AR in 7.62x39 and took it to the range for a test run this morning. The barrel is a YHM 20" melonite barrel, YHM-75. The bolt and carrier are from Tactical Ambush. Upper and lower are Anderson, Anderson LPK. The first round I tried was a Silver Bear, The round fired but did not cycle. When I went to pull back on the charging handle it was stuck. I had to slam the rifle on the butt in a downward motion while pulling on the charging handle to get the spent case out. Next I tried a brass cased Geco round, same result, I tried 3 more Geco rounds and all did the same thing, they chambered and fired but got stuck in the chamber requiring a lot of force to get them to eject. It seened to get slightly easier with each round fired.
I lapped the upper receiver before assembling the barrel. Could this have removed too much material?
HELP!!!!!!!!!!!!!!!

Thanks, Ken

Did you do anything with the chamber?

If you try to rechamber a fired case it will give sticky extraction when you try to pull it out.  That is normal. What could be happening is your rifle is short stroking badly and it is re-chambering the fired case, making it difficult to extract the second time.  Often when this happens the bolt will not be locked all the way up, so, after firing look and see if the bolt is slightly unlocked.  If it is then it is almost certainly short stroking, but it could be short stroking even if it is locked up after firing.  Go back and make sure your gas block is aligned correctly and take measurements, don't just butt the gas block up against the barrel GB shoulder and eye-ball it in there.  Usually the gas block needs to be spaced slightly off the shoulder.  I have seen them needing to be spaced off the shoulder by as much as .050 inch.  While you're at it, check your gas key and rings for excessive leaking, just to cover all your gas bases.  Check these things and w'll take it from there.

Switch out the bolt for a LMT.  Thank me later.

Everything is new and I didn't do anything to the chamber. I didn't think about short stroking, I'll check the gas block alignment and try it again.
Thanks, Ken

Thanks for the feedback. I gave the chamber a quick polish and it is all smooth there. I went to the local indoor range and the rifle is short stroking. I put 1 round in the mag and fired, the bolt did not lock back. I was using Geco brass cased ammo. Then I tried some silver bear, which ejected the case a few times but didn't cycle back far enough to load a round correctly, either closing on an empty chamber or jamming the next round. I did move the gas block slight. It's clearly leaking from where the gas tube goes into the gas block. I was never able to get the rifle to load a second cartridge.
I'll replace the gas block and try this again unless I can fix this, maybe a new gas tube as well.
Thanks, Ken

Here are some pictures, sorry for the quality. The cases were pretty clean, one has a slight dent you can see in the pic. You can see where the extractor grabbed the rim but they are not out of what you would expect. I shot mostly silver bear but didn't keep the cases. These are Geco brass cased ammo in the pictures. I watched the bolt several times when I fired and the bolt just didn't seem to have enough gas to cycle and just pushed the spent case back in most of the time, a few times I had a stove pipe and 5 - 6 of the silver bear ejected but didn't pick up the next round or jammed the next round. I finished by just putting 1 round in the mag and it would eject half of the time. The silver bear seemed to cycle better then the brass cased ammo. When you looked at the barrel with the handguard off there was a clear stream of gas coming from the gas tube towards the receiver with the powder fowling very easy to see where there shouldn't have been any.
Thanks, Ken

The gas tube into the gas block is leaking. There was a 6" long patch of  powder reside on top of the barrel from the gas block back towards the receiver. I don't have an air compressor, but I can probably borrow 1. I should have tried another bolt carrier.
Also this is a rifle length barrel with carbine buffer and tube. It shouldn't make any difference from what I understand, figure I better mention that.
Do the primers look flattened? They looked OK to me, would like to hear from someone who knows more then I do.
Thanks, Ken

The gas block is leaking so do I get a new gas block, new block and gas tube or is there a fix for the leak?

If most of the gas is coming out from the gas tube/gas block junction a little green lock-tite can seal it up.  Normally, gas blocks leak a bit at first untill carbon builds up and seals things off.  It sounds like you have excessive leakage though so a little green lock-tite can help seal the tube/block leak.  However, I do not advise using any lock-tite on the gas block/barrel junction.  It just makes things too much a PITA when you go to remove the GB later on for whatever reason.  
Let me ask this, what kind of gas block are you using?  I have found pinned gas blocks seem to leak more often than a set screw or clamp on.  I know others will disagree but I have never had any problems at all with clamp on or set screw blocks but have had problems with those that are pinned on.  Obviously, they were pinned on incorrectly but that didn't help me any, switching over to a clamp on block cured my problem and it might cure yours.  Personally, I like set screw blocks the best.  The set screws pull the top of the block firmly in contact with the top of the barrel so that would be the type I would advise getting.  Just make sure that when you install it, make sure the ports are aligned by measuring, clean the set screw threads and set screw hole threads and use a half-drop of blue-lock-tite ON THE SCREWS only and snug them down good and tight.

If you already are using a set screw block then either the block is oversized or the barrel GB seat is undersized.  Measure the barrel GB seat and if it measures less than .747 (this is not a firm measurement, just an off the top of my head guestimate) then IMO it is undersized and the barrel is at fault.  If it measures between .747-.750 then it is OK and the GB is likely over sized and the best bet is to replace it with a quality GB from TROY, YHM, VLTOR... nothing off ebay or Amazon.  I like my gas blocks to fit snugly and not a sloppy fit on the barrel, but I have had even very loosely fitting set screw gas blocks work just fine once the screws are snugged down.

I bought a cheap gas block off of ebay, lesson learned. I'll order a new gas block.
I have a new YHM gas block and gas tube on the way.. Hopefully this takes care of my issue.
I checked the barrel diameter and it is right at .750.

Thanks, Ken

When you get your old gas block off check the gas port diameter. I had to open my 20" rifle gassed barrel's gas port to .124" to get it to run. It came from DPMS with a .093" gas port.

Most companies put a .120" gas port on 7.62x39mm rifle gassed barrels. Double check to insure you have a large enough gas port.

Put on a new YHM gas block and new gas tube and took the rifle to the range for a function check. Run 20 rounds of Silver Bear, no issues, bolt locks back on last round. I then  tried some Hornady ammo and that ran fine, no issues. When I tried the Geco brass cased ammo, I was getting FTE 50% (stove pipe) and it would not cycle enough to pick up the next round in the mag. When it didn't stove pipe the bolt closed on an empty chamber, next round fed fine when I cycled the bolt using the charging handle. It seems this ammo is underpowered to cycle the AR. I have plenty of Silver Bear and Hornady. I assume the Geco will be fine in an AK or SKS so I'll sell it and just run the Silver Bear and Hornady ammo.
Thanks for the help.
Ken