mindlessenigma Posted February 26, 2021 Report Share Posted February 26, 2021 hello, this the first rifle i've built, so id like some advice on the issues im having. - 16inch adm uic10 heavy barrel -- .750 jp adjustable gas block.(JPGS5B) i even took it to a gunsmith to make sure it was aligned properly. --i have a rifle length gas tube, and i compared it to the info in this post, and my gas tube appears to be the proper length. i have a jp low mass 308 bcg, and bolt and the buffer/recoil spring is what came with the assembled lower. here is the lower assembly i have https://www.aeroprecisionusa.com/m5-complete-lower-receiver-moe-sl-grip-sl-carbine-stock. i can open the gas system up to the point the adjustment screw is almost falling out of the gas block, and the rifle will still only catch the bolt and hold on a empty mag on a fluke. i haven't been able to replicate it with any reliability. i've seen some posts on the web about issues with a carbine buffer system. id like to keep the adjustable stock, but if i can then so be it. i was wondering what courses of action i can take to make the rifle reliable and have the bolt hold open work. if its the gas system, should i get a non adjustable gasblock? or should i look at the buffer system? ive attached images of the gas tube, and of the rifle. im happy to post more to help yall help me 🙂 Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted February 26, 2021 Report Share Posted February 26, 2021 Your buffer system is definitely part of the problem as the spring and buffer are not the proper size or weight. Take them out and measure them and weigh the buffer but unless something has changed that is part of your issue. It’s not short stroking. It’s moving too fast. Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted February 27, 2021 Report Share Posted February 27, 2021 (edited) ^What he said^ Combine what's already a light buffer that Aero uses with a lighter than normal BCG and the thing is flying. Edited February 27, 2021 by jtallen83 grammar......... Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 so what should i replace my buffer and spring with? Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted February 27, 2021 Report Share Posted February 27, 2021 Measure your parts and the inner tube depth and I’ll give you some recommendations. But I need to be sure Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 27, 2021 Report Share Posted February 27, 2021 (edited) 1 hour ago, jtallen83 said: ^What he said^ Combine what's already a light buffer that Aero uses with a lighter than normal BCG and the thing is flying. Yeah, it is. Gonna need a more-heavy than normal (heavier than 5.4oz) to counteract that lightweight BCG. OP, what's your gas port diameter? And the Gas block journal diameter? Your gas tube length is perfect. Leave your adjustable gas block - just make sure that you're running it wide open,as long as we're doing this testing. Once the gun runs right, worry about adjusting it down. I'd like to see pics of the ADM barrel. 16" rifle gas is rare, so if you can get that rail off and snap a pic, that would be awesome. It's just for the reason of seeing that isn't a Fulton Armory, because they're so rare. I know the Fulton Armory barrel profile had a 0.936" journal, and it had to have a 0.105" gas port to run right, because the dwell time is so short. Edited February 27, 2021 by 98Z5V Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 of course, one sec. and what measurements should i take? Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 the barrel, and barrel nut are a bit scuffed, but thats from me being deft when installing the handguard and having had to take it off so many times. its a adm uic10 16inch heavy. Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 the barrel has a .750 gas port? . im unfamiliar with what the gas block journal diameter is, but the adjustable gas block is .750 as well. here's the barrel https://www.admmfg.com/uic10-barrel-308-win and heres the gas block im using https://www.opticsplanet.com/jp-enterprises-750-adj-gas-block.html Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 i found what i believe to be the buffer tube i have on the rifle, i couldnt find any exact dimentsion though. https://www.aeroprecisionusa.com/ar15-carbine-receiver-extension the specific lower set up i have is this https://www.aeroprecisionusa.com/m5-complete-lower-receiver-moe-sl-grip-sls-carbine-stock from looking at the buffer, i think its aeros general one, https://www.aeroprecisionusa.com/m5-308-carbine-buffer-kit-1 i dont have any scales to weigh it, and im not opposed to changing the buffer tube, spring, or buffer. im guessing that aeros basic set up isint that good. Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 the buffer tube is about 7 inches deep, and heres a pic of the buffer if it helps. Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 could i get your thoughts on adding a bfs3 binary trigger to the rifle? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 27, 2021 Report Share Posted February 27, 2021 (edited) 26 minutes ago, mindlessenigma said: the barrel has a .750 gas port? . im unfamiliar with what the gas block journal diameter is, but the adjustable gas block is .750 as well. here's the barrel https://www.admmfg.com/uic10-barrel-308-win and heres the gas block im using https://www.opticsplanet.com/jp-enterprises-750-adj-gas-block.html Gas block journal diameter is 0.750". That's the gas block diameter that you had to use. The barrel is beautiful - ADM does fine work. No way is the gas port diameter 0.750" - max gas port diameter that any barrel can have is 0.125", since that's the inside diameter of a gas tube. Double check that gas port diameter, if you will. 0.075" is a viable number, but not 0.750"... Edited February 27, 2021 by 98Z5V Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 14 minutes ago, 98Z5V said: Gas block journal diameter is 0.750". That's the gas block diameter that you had to use. The barrel is beautiful - ADM does fine work. No way is the gas port diameter 0.750" - max gas port diameter that any barrel can have is 0.125", since that's the inside diameter of a gas tube. Double check that gas port diameter, if you will. 0.075" is a viable number, but not 0.750"... i looked on their website and online, and i couldn't find the actual measurement for that? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 27, 2021 Report Share Posted February 27, 2021 1 minute ago, mindlessenigma said: i looked on their website and online, and i couldn't find the actual measurement for that? You'd have to pull the gas block - loosen and slide forward - and use a drill index (the small numbered bits) to determine the gas port diameter. That's the easiest way. However it shakes out, you definitely need to get us that number. That's the most important number in figuring all this stuff out. I can come up with a number range that it should be, based on the Fulton Armory proven barrel config, that works. That's 16" rifle gas, 0.936" journal, 0.105" gas port diameter. Give me a few, and I'll edit the post with the port range that you'd need to have. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 27, 2021 Report Share Posted February 27, 2021 Can you put a tape measure up to that barrel, from the upper receiver to the beginning of the muzzle device? That thing looks like 18" rifle gas, not 16" rifle gas... Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 so, when i took it to the gunsmith to check the alignment, he torqued the poop out of the fastening screws. i dont actually know if ill be able to get it off with the little hex key i have Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 worst comes to worst, ill call adm and ask them for the measurement. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 27, 2021 Report Share Posted February 27, 2021 I came up with some bad numbers for a gas port diameter for a 16" rifle gas barrel and a 0.750" gas block journal. You'll need a gas port diameter that's maxed out, 0.125". Let's see what ADM says about it. This is a .308 Winchester cartridge that we're working with here, right? Not 6.5 Creedmoor, 7mm-08, something weird? .308 Win? Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 yep, 308 win. the ammo i have is 150 grain new from freedom munitions Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 27, 2021 Report Share Posted February 27, 2021 Call ADM, man. I hope they planned this thing out the right way. I've never had another 16" rifle gas barrel to compare to the FA barrel - and yours is definitely a 16" barrel. I now know why FA went with a 0.936 gas block journal size. They use that journal size to get the port diameter down from maxed-out. Even the 0.875" would give some wiggle-room, but that 0.750" doesn't leave anything on the table. Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 ok, i just sent them a email. worst comes to worst, would i have to get a gunsmith to resize the port? and out of curiosity how do the differing gas port sizes impact the rifles functionality? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 27, 2021 Report Share Posted February 27, 2021 5 minutes ago, mindlessenigma said: ok, i just sent them a email. worst comes to worst, would i have to get a gunsmith to resize the port? and out of curiosity how do the differing gas port sizes impact the rifles functionality? Gas port diameter is king, in any gas system. It's everything. You don't need a gunsmith to resize the port - you can do that at home, with a hand drill and the right drill bit. I preach that all the time here, and the pilot hole that you need to follow is right there in front of you... Read this when you have the time: Quote Link to comment Share on other sites More sharing options...
mindlessenigma Posted February 27, 2021 Author Report Share Posted February 27, 2021 fucking sweet. thank you so much man Quote Link to comment Share on other sites More sharing options...
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