JimK1075 Posted December 7, 2022 Author Report Share Posted December 7, 2022 13 minutes ago, 98Z5V said: 7 3/4" is too much, and the max you can run is 7 5/8" internal depth, without problems. So, you have a 7 3/4" extension. Stay with me here. 7 3/4" = 7.750". 7 5/8" = 7.625". That means your extension is not correct, but milled another 0.125" too deep. A quarter is 0.069" thick. You need to drop TWO (2) quarters down your extension, THEN put your spring in there and buffer. That's the best solution for your receiver extension, instead of buying one that's machined correctly. What brand of receiver extension is this, or where did you get it? Everyone needs to know to stay away, so it's pertinent details here. The extension is 2a armament. It’s sold as an 8” for the AR308. I think it might have come with a spacer so I’ll look in my parts box. Otherwise I’ll use the quarter trick. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 7, 2022 Report Share Posted December 7, 2022 2 minutes ago, JimK1075 said: The extension is 2a armament. It’s sold as an 8” for the AR308. I think it might have come with a spacer so I’ll look in my parts box. Otherwise I’ll use the quarter trick. There should never be an advertised extension for .308ARs at 8.000". That's not even a right number. If it's 2A, and that's what they're making, and advertising, then they need to find a new vendor, and new supplier for that part. If they're making it themselves, they need to re-look their numbers, because they are OFF. Don't give aftermarket parts vendors a break, if their parts are wrong. Call them out, hope they see it, and fix it. I'll call themon it every single time. Send the right parts, that work, or stop sending your parts out, and we have to come up with a remedy in the future - here. Which we do often. Very often. 2A - if your dimensions are screwed - and fix them, if you're making them. If you're subletting them - fix your sublet vendor. 2A has been very reputable, but if they keep up extensions like this, they're gonna fall into the "shiit-vendor" parts category. Feel free to PM me here, 2A. I'll respond, and give accurate information to you on how to make this part correctly. There is no excuse. Quote Link to comment Share on other sites More sharing options...
JimK1075 Posted December 8, 2022 Author Report Share Posted December 8, 2022 @98Z5V I got 1 more turn on the buffer extension. I added 2 quarters and I inserted the spring and buffer. I pushed BCG into the buffer tube all the way and it appears to be about 3/16” clearance. Wondering if this seems like too much. How much clearance is the right amount? Quote Link to comment Share on other sites More sharing options...
shooterrex Posted December 8, 2022 Report Share Posted December 8, 2022 Put the upper on and check the distance between the face of the bolt and the bolt catch w/the bolt held all the way back. Between 1/8 and 3/8 is good. Quote Link to comment Share on other sites More sharing options...
JimK1075 Posted December 8, 2022 Author Report Share Posted December 8, 2022 @shooterrexthanks I’ll do that. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 9, 2022 Report Share Posted December 9, 2022 21 hours ago, JimK1075 said: @98Z5V I got 1 more turn on the buffer extension. I added 2 quarters and I inserted the spring and buffer. I pushed BCG into the buffer tube all the way and it appears to be about 3/16” clearance. Wondering if this seems like too much. How much clearance is the right amount? Jim, there's no defined standard for the amount of clearance between BCG and lower. That looks good, though. Keep in mind, under recoil, the bumper on the end of that buffer will compress... Looks like you have enough clearance to not worry about it. The math on 2 Quarters is correct, as well as the internal depth that you gave us. Quote Link to comment Share on other sites More sharing options...
JimK1075 Posted December 9, 2022 Author Report Share Posted December 9, 2022 @shooterrex@99ZV5 after the 2 quarters and adding 1 more turn on the buffer tube my bolt has about 1/8-3/16” travel after the bolt catch so mechanically I think I’m set. Thanks for helping me troubleshoot this because it’s saved me hours of browsing the net and these forums for answers. Now I need to find my Allen key so I can set up my adjustable gas block and next I can go fire this beast. Surprisingly there’s not a lot of guys that actually know how to troubleshoot these and get them set up so they run like they should. I can’t wait to get out to the range! Quote Link to comment Share on other sites More sharing options...
shooterrex Posted December 9, 2022 Report Share Posted December 9, 2022 If you start w/the gas block wide open and close it a bit at a time till the bolt won't lock back you'll save some time and ammo. Then just open it up a bit after it doesn't lock back. Quote Link to comment Share on other sites More sharing options...
JimK1075 Posted December 9, 2022 Author Report Share Posted December 9, 2022 8 hours ago, shooterrex said: If you start w/the gas block wide open and close it a bit at a time till the bolt won't lock back you'll save some time and ammo. Then just open it up a bit after it doesn't lock back. Yeah that’s what I had planned. For some reason the directions say to start with it closed but I don’t follow that logic. I plan to open it up all the way and get some rounds through it and loosen it up while I’m dialing in my optic. I’ll close it bit by bit until the bolt doesn’t lock back and then open it up until it does and then just a bit more. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 10, 2022 Report Share Posted December 10, 2022 9 hours ago, JimK1075 said: I plan to open it up all the way and get some rounds through it and loosen it up while I’m dialing in my optic. I’ll close it bit by bit until the bolt doesn’t lock back and then open it up until it does and then just a bit more. ^^^ That's the way to do it. Quote Link to comment Share on other sites More sharing options...
JimK1075 Posted December 11, 2022 Author Report Share Posted December 11, 2022 @98Z5V 👌 Quote Link to comment Share on other sites More sharing options...
Traveler Posted December 12, 2022 Report Share Posted December 12, 2022 Looks like you have the best assistance you can get! I for one am looking forward to hearing about your range trip. Welcome from NC! Semper Fidelis! Mike Quote Link to comment Share on other sites More sharing options...
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