fhfirefighter Posted November 15, 2022 Report Share Posted November 15, 2022 Hi guys. First, I would like to thank all of you for your infinite wisdom on all things AR10 and your willingness to explain over and over to people why their rifle won't run when if they had spent a few minutes researching your forum the answer is right there. Over and over again. More often than not it's the wrong buffer tube, too light a buffer, wrong spring and incorrect gas port diameter. What's more amazing to me, when you explain it to them in great detail, they second guess you, do their own thing and ask again what's wrong until ultimately, they do like you said and like the seas parted, problem solved. So, with all of that being said I think i have a handle on it, I think. I do have a couple of problems i need yalls math skills for so there we go. I am building two different 308 rifles, and everything is going to be the same with the exception of barrel length, handguard/rail length, gas length and triggers. The upper and lower are both Aero Precision M5's. Barrel #1 is a Criterion M118 Hybrid 18 inch 308 4150 CrMoV Nitride finish with Mid-length gas. It has a .750 gas block journal and I going to be using an Aero adjustable gas block. The gas port is 0.070 and from the center of the port to the end of the barrel at the threads it measures 8 5/16 inches. I am going to run a Midwest Industries 15-inch combat rail and finish the business end off with the Precision Armament M4-72 Severe Duty brake. I'm going to be using a Rise Armament 535 advanced performance drop in trigger. I am running the XH carbine buffer and spring from HeavyBuffers.com that this site recommends. The buffer tube was also purchased from Clint. It's paired to a Magpul PRS Gen3 stock as I plan on this being more of a DMR. I have both am Aero BCG and a CMC BCG but haven't decided yet which to use. Any input there would be appreciated. Barrel #2 is a Ballistic Advantage 12.5-inch 308 Tactical Government Modern Series 4150 CrMoV Nitride finish with Carbine length gas. It has a .750 gas block journal, again using an Aero adjustable gas block. The gas port is 0.063 and from the center of the gas port to the threads at the end of the barrel measures 4.95 inches. Like I said. I really need yalls math skills to figure out what my gas port diameters on both barrels should be, so they run and run all the time. sorry for the length of this but as they say, the devil is in the details. Thank you all in advance. Quote Link to comment Share on other sites More sharing options...
BrianK Posted November 15, 2022 Report Share Posted November 15, 2022 Since I don't know squat about anything AR10 I'll just give a welcome. Welcome to the forum! Quote Link to comment Share on other sites More sharing options...
98Z5V Posted November 16, 2022 Report Share Posted November 16, 2022 (edited) 4 hours ago, fhfirefighter said: Barrel #1 is a Criterion M118 Hybrid 18 inch 308 4150 CrMoV Nitride finish with Mid-length gas. It has a .750 gas block journal and I going to be using an Aero adjustable gas block. The gas port is 0.070 and from the center of the port to the end of the barrel at the threads it measures 8 5/16 inches. 18" midlength gas and a 0.750" journal needs 0.085" for a gas port. 4 hours ago, fhfirefighter said: Barrel #2 is a Ballistic Advantage 12.5-inch 308 Tactical Government Modern Series 4150 CrMoV Nitride finish with Carbine length gas. It has a .750 gas block journal, again using an Aero adjustable gas block. The gas port is 0.063 and from the center of the gas port to the threads at the end of the barrel measures 4.95 inches. 12" or 12.5" carbine gas and a 0.750" journal needs 0.070" for a gas port. Two (2) criteria there on those numbers: 1) we're talking about something chambered for .308 Winchester. 2) we're talking about a proper recoil system, with a buffer weight of 5.4oz (or very close), matched to the appropriate recoil spring. If it meets that criteria, the numbers I gave you for port diameters will work like a champ. You stated the caliber and recoil systems, so that's not so much directed at you - that's for some dumbass in the future that's running a .243 or 7mm-08, quotes those numbers, then says his shiit doesn't work right, and we're wrong... Welcome aboard! Edited November 16, 2022 by 98Z5V Quote Link to comment Share on other sites More sharing options...
Armed Eye Doc Posted November 16, 2022 Report Share Posted November 16, 2022 Welcome to the forum from a fellow Texan. Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted November 16, 2022 Report Share Posted November 16, 2022 Welcome from Iowa! Quote Link to comment Share on other sites More sharing options...
Rsquared Posted November 16, 2022 Report Share Posted November 16, 2022 Welcome from Maryland. Quote Link to comment Share on other sites More sharing options...
Armed Eye Doc Posted November 16, 2022 Report Share Posted November 16, 2022 @fhfirefighter where in Texas are you... generally speaking? Quote Link to comment Share on other sites More sharing options...
shooterrex Posted November 16, 2022 Report Share Posted November 16, 2022 Welcome from KY. Quote Link to comment Share on other sites More sharing options...
JMJ Posted November 16, 2022 Report Share Posted November 16, 2022 Welcome from Louisiana! Quote Link to comment Share on other sites More sharing options...
fhfirefighter Posted November 23, 2022 Author Report Share Posted November 23, 2022 Thank you all very much for the welcome to the forum. As i previously stated i have been reading and trying to absorb everything I can with the larger format and obviously this is the right place and yall are the right people to ask. I'm sorry it's taken me a bit to respond but between a birthday and getting ready for Thanksgiving as you know it's a busy time for all. Armed Eye Doc I am just a stone's throw west of Ft. Worth. 98Z5V, thanks for the info. I will get them drilled tomorrow, I'm sure. I knew you would have not just an answer but the correct one so thanks again. Yes, the recoil situation is completely sorted because I was able to find and follow yalls suggestion and firm belief in Heavybuffers.com. He got me hooked up after a couple of emails. Glad to see so many states represented and supporting our 2nd! Thanks to all again for the welcome and the solid information. I will let yall know as soon as I'm up and running. Yall have a Happy Thanksgiving a blessed Christmas, and a Happy New Year. Talk to yall soon. Quote Link to comment Share on other sites More sharing options...
Armed Eye Doc Posted November 23, 2022 Report Share Posted November 23, 2022 I grew up in FW and live 1.5 hrs SE of there now. Still have family in and around there including close to where you live. Quote Link to comment Share on other sites More sharing options...
Cunuckgaucho Posted November 23, 2022 Report Share Posted November 23, 2022 Welcome from BC Quote Link to comment Share on other sites More sharing options...
unforgiven Posted November 23, 2022 Report Share Posted November 23, 2022 Welcome from Indiana brother Quote Link to comment Share on other sites More sharing options...
JimK1075 Posted December 3, 2022 Report Share Posted December 3, 2022 Welcome from California Quote Link to comment Share on other sites More sharing options...
Traveler Posted December 12, 2022 Report Share Posted December 12, 2022 Welcome from NC! Semper Fidelis! Mike Quote Link to comment Share on other sites More sharing options...
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