Albroswift Posted September 30, 2019 Report Share Posted September 30, 2019 Going to town on the 6.5 Creedmoor build, checked the gas port, .062 no go .059 go. .875 journal. Mid length gas. Is that the correct port size? Seems small, but nothing to compare to. Interesting factoid, the BA barrel uses the 11-3/4" tube, not the 12-1/16. Assembled with 12-1/16"tube, visually way past center of cam cutout, and confirmed bolt will not close. Didn't have a 11-3/4"" laying around. Quote Link to comment Share on other sites More sharing options...
MikedaddyH Posted September 30, 2019 Report Share Posted September 30, 2019 Saw a large variety of 6.5 Creedmore ammo at LGS' this weekend. Might do a build next year. I like mid length gas systems , they smooth out the cycling actions of the larger framed AR's and reduce the felt recoil over a carbine length system. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted October 1, 2019 Report Share Posted October 1, 2019 13 hours ago, Albroswift said: Going to town on the 6.5 Creedmoor build, checked the gas port, .062 no go .059 go. .875 journal. Mid length gas. Is that the correct port size? What's the length of the barrel, man? Quote Link to comment Share on other sites More sharing options...
Albroswift Posted October 1, 2019 Author Report Share Posted October 1, 2019 18" BA, the one I bought from Concretus a couple of months back. Quote Link to comment Share on other sites More sharing options...
Albroswift Posted October 1, 2019 Author Report Share Posted October 1, 2019 1:8 18" Quote Link to comment Share on other sites More sharing options...
98Z5V Posted October 2, 2019 Report Share Posted October 2, 2019 (edited) Damn. That sucker is small. Based on the barrel diameter at the gas port, I'm gonna say that you'll need 0.080"~0.085" gas port diameter. Crazy, right? Make small steps until it functions, but if it was mine, I'd go straight for 0.070" and move up from there in 0.005" increments until it runs right. EDIT - just on a weird note - shoot it like that and see what happens... Edited October 2, 2019 by 98Z5V Quote Link to comment Share on other sites More sharing options...
Albroswift Posted October 2, 2019 Author Report Share Posted October 2, 2019 it reportedly cycled several different types of ammo both factory and reloads. Don't know what spring/ buffer combo. We are going with an adjustable block anyway and the armalite extension/ spring/ buffer so I'm thinking just go to .080 diameter to start and do my adjusting without several trips between the drill press and the range. That drill press part is stressful! Hunting season starting so probably won't be going to the range for a while. Quote Link to comment Share on other sites More sharing options...
Albroswift Posted October 2, 2019 Author Report Share Posted October 2, 2019 Going back and forth from messaging Concretus and this thread, he was running rifle length extension tube, 308 rifle buffer, tubbs 308 spring, superlative adjustable gas block. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted October 3, 2019 Report Share Posted October 3, 2019 14 hours ago, Albroswift said: Going back and forth from messaging Concretus and this thread, he was running rifle length extension tube, 308 rifle buffer, tubbs 308 spring, superlative adjustable gas block. That's a 5.4oz buffer, right there. You'll need the armalite stuff to make it comparable. That port just seems small as hell, and isn't anything like others that I've seen. Try that sucker out. Quote Link to comment Share on other sites More sharing options...
Albroswift Posted October 3, 2019 Author Report Share Posted October 3, 2019 Correct. I'm using the armalite carbine extension kit, so buffer is 5.4 oz as well. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted October 4, 2019 Report Share Posted October 4, 2019 Shoot it, as is, in your hands - don't drill anything... Let's figure this thing out. Quote Link to comment Share on other sites More sharing options...
Albroswift Posted October 4, 2019 Author Report Share Posted October 4, 2019 Copy that. It'll be on the bench for a little while, getting out for some hunting. Dragging the trailer down to camp this weekend. Quote Link to comment Share on other sites More sharing options...
Albroswift Posted February 8, 2020 Author Report Share Posted February 8, 2020 On 10/3/2019 at 9:40 PM, 98Z5V said: Shoot it, as is, in your hands - don't drill anything... Let's figure this thing out. OK, ready to figure? We spent a couple hrs + at the range this morning. The details for a reminder: 0.060 +/- gas port midlength gas dead center cam cutout .875 journal Seekins adjustable block Toolcraft BCG 18" BA barrel Started with Armalite ea1095 spring, Armalite 5.4 buffer, Armalite 308 extension tube Wouldn't cycle or lock back Adjusted block all the way out. No Joy. Went to Sprinco Red Spring. No Joy. Took gas block off, inspected, and reinstalled. 4.6 buffer. 4.0 buffer. No Joy. Worked all the way down to AR15 carbine spring and H1 buffer, WooHoo! Ran a few single and double loads and 2 magazines full with LRBHO 100%. Tedious! Fully functional. Good groups factory ammo, 125 and 140 gr w/ AR15 Carbine spring and buffer in a 7-5/8" Armalite tube. Forget everything you learned about 308's... Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted February 8, 2020 Report Share Posted February 8, 2020 19 minutes ago, Albroswift said: OK, ready to figure? We spent a couple hrs + at the range this morning. The details for a reminder: 0.060 +/- gas port midlength gas dead center cam cutout .875 journal Seekins adjustable block Toolcraft BCG 18" BA barrel Started with Armalite ea1095 spring, Armalite 5.4 buffer, Armalite 308 extension tube Wouldn't cycle or lock back Adjusted block all the way out. No Joy. Went to Sprinco Red Spring. No Joy. Took gas block off, inspected, and reinstalled. 4.6 buffer. 4.0 buffer. No Joy. Worked all the way down to AR15 carbine spring and H1 buffer, WooHoo! Ran a few single and double loads and 2 magazines full with LRBHO 100%. Tedious! Fully functional. Good groups factory ammo, 125 and 140 gr w/ AR15 Carbine spring and buffer in a 7-5/8" Armalite tube. Forget everything you learned about 308's... 60 thou is a tiny little gas port, I'd say that sucker could afford to be drilled up. Quote Link to comment Share on other sites More sharing options...
Albroswift Posted February 9, 2020 Author Report Share Posted February 9, 2020 Original owner said he was running sprinco orange and heavy buffer. Must have had some gorilla loads. Plan on opening up the port a bit. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 9, 2020 Report Share Posted February 9, 2020 Yep, I'd cut that port up. Go north, brother. 0.875" gasblock journal changes the numbers I gave you before - add another 0.005" to what I gave you earlier (instead of 0.080"~0.085", you're gonna need 0.085"~0.090" on that port.) Journal size matters. Quote Link to comment Share on other sites More sharing options...
Albroswift Posted February 9, 2020 Author Report Share Posted February 9, 2020 (edited) On 10/1/2019 at 8:52 PM, 98Z5V said: EDIT - just on a weird note - shoot it like that and see what happens... Yes and your welcome for the data! So it's possible to have an AR15 recoil spring and 3 oz buffer in a large frame, only downside I could see is the spring probably couldn't overcome a little fouling. We'll drill it up, see how it runs with the heavy buffer and spring. Also maybe try the 4.6 oz buffer and red sprinco combo seeing how I have nothing better to do until hunting season then to gather data for the team . Al Edited February 9, 2020 by Albroswift Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted February 9, 2020 Report Share Posted February 9, 2020 1 hour ago, Albroswift said: only downside I could see What's the brass look like? With that weak recoil system it has to be opening up early. Quote Link to comment Share on other sites More sharing options...
Albroswift Posted February 9, 2020 Author Report Share Posted February 9, 2020 4 hours ago, jtallen83 said: With that weak recoil system it has to be opening up early. Not at all. Brass looked fine. Any heavier wouldn't open at all or come about halfway open and close back up. The second to lightest buffer the spent brass would either barley clear the chamber or get caught. Think that was 4oz buffer/ AR15 carbine spring. Started heavy and went lighter and lighter spring and buffer until reliable feed and LRBHO. Totally under gassed. Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted February 9, 2020 Report Share Posted February 9, 2020 Guess it all about balance. Quote Link to comment Share on other sites More sharing options...
Albroswift Posted February 10, 2020 Author Report Share Posted February 10, 2020 This was the tedious balance, no idea why I grabbed a box with this boneyard collection in it but I had it with me. Springs: Armalite EA1095 Sprinco Red Ar15 Carbine (Glad I didn't have a sprinco orange with me...) Buffers: Armalite 5.4 Expo Arms (H3) 5.2 Expo Arms (H2) 4.6 Expo Arms (H1) 4.0 Ar15 Carbine 3.0 Quote Link to comment Share on other sites More sharing options...
Albroswift Posted March 14, 2020 Author Report Share Posted March 14, 2020 On 2/8/2020 at 6:58 PM, 98Z5V said: Yep, I'd cut that port up. Go north, brother. 0.875" gasblock journal changes the numbers I gave you before - add another 0.005" to what I gave you earlier (instead of 0.080"~0.085", you're gonna need 0.085"~0.090" on that port.) Journal size matters. Opened that baby up to .087, put the Armalite recoil parts back on, too much gas. Cranked the Seekins AGB down to about 2.5 turns, shooting sweet. 4 different factory loads in the 120-150gr range, all good ran out about 60 rounds 100% reliable. Tuning question for someone smarter then me: Ejection pattern 1:00 Cranked in gas block a little more, bit by bit all the way to no LRBHO and brass falling right out onto the shooting bench but could never get past 1:00. Went the other way until signs of too much bolt speed ditto. Maybe go to a 6.8oz buffer and a little more gas? Dual ejector? Or no big deal... Quote Link to comment Share on other sites More sharing options...
98Z5V Posted March 14, 2020 Report Share Posted March 14, 2020 (edited) 23 minutes ago, Albroswift said: Or no big deal... IMHO, if it gets out of the gun, every single time, it's no big deal. However, if you want to change that ejection pattern - that's buffer weight, just like you thought, or a heavier spring. Sprinco Red spring. Either one will do it. The spring is cheaper, brother. you also have adjustable gas - put another 1/2 turn in it and see what happens, go 3 turns instead of 2.5 - THAT is the easiest - it's free, since you already have that capability. Edited March 14, 2020 by 98Z5V Quote Link to comment Share on other sites More sharing options...
Albroswift Posted March 14, 2020 Author Report Share Posted March 14, 2020 1 hour ago, 98Z5V said: Sprinco Red spring Is a Sprinco red heavier then an EA1095? have one left over from the AR40 tuning sessions. I also have a Tubbs flat wire spring, AKA "the biggest PITA to install/ uninstall" spring. 1 hour ago, 98Z5V said: put another 1/2 turn in it and see what happens, 1 hour ago, Albroswift said: Cranked in gas block a little more, bit by bit all the way to no LRBHO and brass falling right out onto the shooting bench but could never get past 1:00 Maybe just call it a win and move on to load development. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted March 15, 2020 Report Share Posted March 15, 2020 1 hour ago, Albroswift said: Is a Sprinco red heavier then an EA1095? Yes, ever so slightly. It's enough to make a difference, though. . Since you have one, slam it in and try it, man. It'll change your ejection pattern - but it will be cool to hear how much, from a firsthand prospective. Quote Link to comment Share on other sites More sharing options...
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