Mrj209 Posted July 30, 2021 Report Share Posted July 30, 2021 Hey so I'm on my first 308 build. It's a live free armory upper and lower, 20 inch ballistic advantage barrel. With a rifle length gas system. KAK carbine buffer system. 5.4 oz buffer that is 2.5 in long. Internal buffer tube length is right at 7in. SPRINGCO carbine Spring is 11in long and has 27 coils. Rifle length gas tube is 15 and 1/8th in long. Gas port is .086in and the shoulder is .750. Odin works adjustable gas block. Bolt won't lock back on last round or pick up new round. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 31, 2021 Report Share Posted July 31, 2021 (edited) The gas port is too small. Make sure, positively, that you're breaking this thing in and getting it running, with that adjustable gas block wide open. Not restricted at all. All the other parts in your build look spot-on, but that gas port is barely adequate. Edited July 31, 2021 by 98Z5V Quote Link to comment Share on other sites More sharing options...
Mrj209 Posted July 31, 2021 Author Report Share Posted July 31, 2021 @98Z5V I read your thread about ar308 building and I was thinking the same thing. Unless it's something very small and out of spec, that seems like a likely candidate. Can I open up the port with a hand drill and a rod in the barrel to protect the rifling? Or do I need a drill press or other tools? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 31, 2021 Report Share Posted July 31, 2021 1 minute ago, Mrj209 said: @98Z5V I read your thread about ar308 building and I was thinking the same thing. Unless it's something very small and out of spec, that seems like a likely candidate. Can I open up the port with a hand drill and a rod in the barrel to protect the rifling? Or do I need a drill press or other tools? Hand drill and a numbered drill bit is easy to do. Go slow on the drill speed, use some oil on the bit, and only apply very light pressure to the drill. Let the bit do the work. 1/4" wooden dowel down the barrel is never a bad idea. I'd punch that thing up to 0.090" and see how it acts. Or, since you do have an adjustable gas block on there, just knock it out to 0.095", run it, and tune it down a little with that adjustment. Little Machine Shop is my favorite reference for the drill bit sizes: https://littlemachineshop.com/reference/numberdrillsize.php Quote Link to comment Share on other sites More sharing options...
Mrj209 Posted July 31, 2021 Author Report Share Posted July 31, 2021 I have a #42 bit on hand. Unfortunately I need a replacement part for my gas block as i had it so completely open I blew the screw down range. It'll be a few days before I can check to see if this does the trick. Thanks for the info @98Z5V Quote Link to comment Share on other sites More sharing options...
DNP Posted July 31, 2021 Report Share Posted July 31, 2021 …just stuff a thumb in it. no…don’t do that. I imagine that wouldn’t end well. Quote Link to comment Share on other sites More sharing options...
LR308Shootin@45 Posted July 31, 2021 Report Share Posted July 31, 2021 I agree with 98Z5V, gas port was off spec and I also agree no more than .095". I had to do this to a 308 barrel as well. I used a drill press to drill out the port slowly. Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted July 31, 2021 Report Share Posted July 31, 2021 7 hours ago, DNP said: …just stuff a thumb in it. no…don’t do that. I imagine that wouldn’t end well. Quick derail, had a guy grab the end of my M60 blank adapter while I was firing. Wasn't as devastating as I would have thought but it did blow out the back of his glove, you couldn't see through his hand though........... 10 hours ago, Mrj209 said: Can I open up the port with a hand drill and a rod in the barrel to protect the rifling? Just like 98 said and you won't have an issue...... just don't use cheap bits for this job. Quote Link to comment Share on other sites More sharing options...
Mrj209 Posted July 31, 2021 Author Report Share Posted July 31, 2021 @DNP I love how Kentucky Ballistics' catastrophic malfunction with the Serbu 50 has created a fun catch phrase Quote Link to comment Share on other sites More sharing options...
DNP Posted July 31, 2021 Report Share Posted July 31, 2021 I hope the phrase continues to carry his story. It just works for so many things. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted August 1, 2021 Report Share Posted August 1, 2021 Buy some shirts and support the guy. In hindsight, he was doing this for the community, when that gun blew up. And Demolition Ranch is who produces those shirts anyway, so you're supporting that, too. The guy that was installing all the security camera system stuff on GunPusher John's new shop today was wearing one... Quote Link to comment Share on other sites More sharing options...
Mrj209 Posted August 5, 2021 Author Report Share Posted August 5, 2021 Hey everyone, just wanted to give you an update. Resized the gas port to 0.09375 from 0.086 and boy howdy did that do the trick. Had to close off the gas port a bit to get it tuned in but it's running like a silver bullet train now. Thanks for your help, even though the first thing I tried didn't do it, the very first post anyone ever have me advice in mentioned the gas port. You're all awesome, and thanks again! Quote Link to comment Share on other sites More sharing options...
Armed Eye Doc Posted August 5, 2021 Report Share Posted August 5, 2021 Awesome job! Thanks for the update. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted August 6, 2021 Report Share Posted August 6, 2021 Great update @Mrj209 !!! glad it's running like it's supposed to! I get lucky with that gas port shiit every once in awhile - glad it worked out this time. Quote Link to comment Share on other sites More sharing options...
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