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9/20/2015 10:22:42 PM EDT
I built a pair of 7.62x39 's, 7.5" and 16". The 16" is running flawlessly, but I took the 7.5" out to test at the range today and it gave me the blues.

I'm running a Spike's T2 buffer and standard spring with an adjustable gas block. I was running single rounds in the mag trying to get the gas adjusted to lock back on empty. I went from all the way closed to all the way open, about midway through I started to get consistent ejection but never got the bolt to lock back on empty. It was moving back enough to reset the trigger though.

I've got some extra bcm o-ring and springs so I will throw a set on the bolt to help with extraction. But what next? Lighter buffer?
9/20/2015 10:50:30 PM EDT
[#1]
Might try a lighter buffer.
If you have a FA carrier in it you might try semi.
9/21/2015 10:46:11 AM EDT
[#2]
Whats the model of the barrel?
9/21/2015 11:07:15 AM EDT
[#3]
Radical firearms for both 7.5" and 16"

I've been thinking about bumping up to a 10.5" barrel if I can find a good deal on one.
9/21/2015 2:35:31 PM EDT
[#4]
Pistol gas on the 7.5", right?  What's the port diameter?

Try a carbine 2.9oz buffer first. Hold onto the St-T2 if you plan to suppress it, which is the only real reason I can think of having a 7.5" AR.
9/21/2015 2:36:01 PM EDT
[#5]
I had 4 of the 7.5" Radical barrels. Each one had to be opened up a tad to get it to run 100% using Red Army Standard Ammo. If I soaked the BCG in oil, it would run, but after I opened up the gas port, and tried with a moderate amount, they all ran perfect.
9/21/2015 2:50:35 PM EDT
[#6]
Quote History
Quoted:
I had 4 of the 7.5" Radical barrels. Each one had to be opened up a tad to get it to run 100% using Red Army Standard Ammo. If I soaked the BCG in oil, it would run, but after I opened up the gas port, and tried with a moderate amount, they all ran perfect.
View Quote


Thanks for the info. I'm still rather new to tuning AR's but I felt like I was heavily undergassed. Do you know what size you ended up with? I don't really have the resources to make multiple trips to the range to step up each diameter and I don't think the range will let me bring my portable drill in. However I just might try to, the worse they can do is tell me I can't use it.
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