Armalite 7.62x39 short stroking....HELP

hicaliber

hicaliber

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I have a brand new Armalite in 7.63x39 that is short stroking, waiting to hear back from the dealer but looking for advice.
First range trip it was not feeding properly and I had to rack it almost every shot, the gun was cleaned and oiled prior to that range trip.
Fired about 120 rounds first time out.

I brought the gun home and stripped it down again and cleaned it, greased the sh*t out of it and took it out again last night.
Doing exactly the same thing.
I generously oiled it at the range, same thing.
I know they need a couple of hundred rounds to break in so I put another 160 through it last night, no difference.

During the first range trip I noticed the gun was short stroking and the bolt was not coming all the way back which is why it wouldn't strip another round off. It was the same thing last night.
You can see in the pic that on the last round the bolt doesn't go back all the way, this is where it catches and is held open.

I'm thinking the buffer spring is too heavy and causing it too short stroke.
Can I swap in a .223 buffer spring and is there a difference between the two?

I don't want to do anything drastic that will mess with the warranty but hoping someone has a simple fix for this.....HELP PLEASE!

 
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From my experience never heard of a "different" spring

You manually chamber a round and then remove the mag and fire it and see if it not a mag issue? I know with alot in the earlier years of 7.62x39 AR it always came down to a GAS issue.
 
Check your barrel extension to see if there m4 223 feed ramps if so
You will have to get them widened. Most of the time eith FTF
Its the feed ramps, 7.62x39 is a tapered round doesnt work well with
223 feed ramps, either widen them with and dremle and polish them
Or make one big feed ramp and polish it.

What kind of mags are you using?
 
I think you would need a heavy buffer h3 and more gas. Id check the gas
Issue before anything else. They havent worked alot of the problems
Out of thiscaliber ar sonetimes all you need is a bigger gas hole some sonetimes even an
33/16th gas hole
 
You mentioned grease, I've found that some of my rifles won't cycle with grease in the winter, try some gun oil and see what happens.
I hope it's that simple :)
 
Thanks for the replies.
It was Norinco ammunition, also tried some Czech surplus.
Gun is brand new Armalite so wear is not an issue.
Using factory M-15 MAG and XCR 10 rd pistol mags.
Used oil and tried the grease because it was suggested, I was in a heated range both times, not outside.
If it's a gas or feed ramp issue then back to the dealer it goes, I expect a new gun to work properly and screwing with it will void any warranty.
I have 2 other AR's in .223 and racking this one is a real chore compared to the others which is the reason I wondered if they used a heavier buffer spring for 7.62.
Thanks again for the suggestions.
 
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Yeah they are still really working the kinks out. But you will get
It figured out man, im going adams arms piston system in mine
I cant wait to shoot it
 
Check the buffer roll pin if it has one. I have seen them start to come out and cause friction in the receiver extension tube (buffer tube).

Depending on what the manufacturers spec is on the gas port, you could check that. Lastly, there are different buffer springs strengths available. Not sure if the manufacturer can tell you if it is a regular carbine type spring or a heavier 9mm type spring (or something proprietary to their design).

Oh, don't use grease on the BCG to receiver contact points, use oil.
 
I'm no expert, but the guy who built my 7.62x39 upper is. He sent along a shortened buffer spring and a H2 buffer. I can use the H2 buffer with norcy ammo but it isn't reliable with european surplus. To shoot Czech I have to put a standard weight buffer in it and then it works 100 percent. Based on my own experience I wouldn't put a heavier buffer in it. x39 runs at lower pressures than 5.56/.223 so it's possible that your rifle is undergassed for the spring and buffer combination. They don't run well with off the shelf parts, that much I've learned with mine.
 
Spoke to the Armourer at Wolverine and you guys were correct,he seems pretty certain the gun is under gassed. The upper is on it's way back to be checked and have the gas port opened up if needed.
Thanks for all the advice.
 
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