AR15 7.62x39 extraction/ejecting issues

[Velzey]

I checked my notes and see my Colt 7.62x39 carbine has a gas hole of .125. I also run a JP adjustable gas block. But that is just to help me find my brass. I like to adjust it down to where it tosses it out about 2' away instead of 25' into the abyss of blackberries.

If you drill your gas hole, go slow as so not have the drill grab and go thru the hole quick and have the drill point damage the rifling on the opposite side

 

[Member 34319]

ARD is American rifle depot. They turn out inexpensive stuff, not always to spec. They ploy that there stuff is pretty good though.

I'd drill her out if I were you. Start with .113 and work up if needed.

 

[Scot4ever]

Thanks, I'll do that and be sure to take it easy. I'll let you know how it goes after I get out to the range.

 

[jbett98]

You can put a wood dowel into the barrel as a back stop when drilling.

 

[Scot4ever]

Got the gas port drilled out to 0.108 (closest I could go to 0.113, next smallest drill I have is 0.122) and just got back from test firing. Single round in the mag each time fired a total of 6. All stripped cleanly from the mag as the bolt went forward and the bolt locked back each time.
#1 ejected at about 1 o'clock and flew 3-5 feet. #2 ejected at 3 o'clock and flew about 2 feet. #3 dropped on the firing bench. #4 was in a stovepipe position against the locked open bolt. #5 lay in the open port and #6 was in the open port with the neck partially in the chamber.
I can re drill the gas port but should I take it as wide as 0.122 or try to find a smaller drill bit to get it somewhere in between 0.113 and 0.122 first. Here's a photo of the fired brass. They all seem to be pretty dirty too. Is that normal?

 

[Member 34319]

Sounds like it got worse as you shot.

Also sounds like it improved.

May be that your gas block walked? That's all I can think of for it getting worse as you progressed.

Go get yourself a bit close to the 113 marker. And a few larger just in case. Opening it up slowly till it cycles best.

Also. You can mark your barrel where your Allen nuts meet for your gas block and drill a divot for them to sit in. This should prevent any walking, if that is happening.

Good luck! Gas issues are ole so fun. Especially trying to find that sweet spot where everything runs.

 

[Scot4ever]

I've been working through my issue and so far have taken the gas port up to 0.114 methodically testing as I go. Whereas I was getting some ejections in my previous post ( gas port at 0.108) that got worse as I fired, I'm now getting a continuous fired casing laying in the open port. My next step was to drill the gas port to 0.119 but before I charge ahead with that I'm noticing that when I remove the gas block I can see visible signs of gas leakage almost round the entire circumference of the barrel and also inside the gas block. Has anyone seen this before? Could I have a dodgy gas block? The gas block port and barrel gas port should be in alignment as I put some registration marks to help me line them up. I also drilled recesses for the gas block set screws so it's not moving when fired.

 

[Scot4ever]

This is what I meant by gas leaking around the barrel at the gas port. Side view with gas port located at top.

 

[Scot4ever]

Ugh! Never mind. Just discovered the extractor is broken at the top. I think I may take off the donut O-ring around the extractor spring to see if that reduces the stress when I replace the extractor.

 

[Scot4ever]

Update. Fit a new extractor and decided to remove the donut ring. Fit an adjustable gas block which I closed all the way then backed it out 1 turn. Bought a c-mag magazine. Removed the barrel and polished the chamber one last time with blue magic. Went to the range and ran a couple dozen rounds of federal and PPU through it and it ran as sweet as a nut. All the casings ejected at five o'clock and landed pretty much in the same place. Thanks to all who offered advice, I learned a lot.