Modo Posted March 9, 2015 Report Share Posted March 9, 2015 I have a 16 inch 308 barrel that's rifle gassed, I'm having a had time with short stoking. Seems it's running under gassed and needs an adjustable gas block. Any idea what size the barrel gas port should be? Having a hard time cycling ZQI 762 from Walmart. Quote Link to comment Share on other sites More sharing options...
DNP Posted March 9, 2015 Report Share Posted March 9, 2015 It was once wisely pointed out to me that an adjustable gas block can only lower the ammount of gas flow. Makes sense, yeah? So if you need to make adjustments, you'll have to either open up the port, or lighten up the moving parts. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted March 9, 2015 Report Share Posted March 9, 2015 I have a 16 inch 308 barrel that's rifle gassed, I'm having a had time with short stoking. What manufacturers barrel is this? Is it a Fulton Armory/Criterion barrel that you're talking about? If not, who's is it? Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted March 9, 2015 Report Share Posted March 9, 2015 I feel a "four letter word" coming on.... Modo, what stock assembly are you using? What muzzle device? Quote Link to comment Share on other sites More sharing options...
DNP Posted March 9, 2015 Report Share Posted March 9, 2015 Lets move this to it's own topic. Fixed. Thanks! -Robo Quote Link to comment Share on other sites More sharing options...
Modo Posted March 9, 2015 Author Report Share Posted March 9, 2015 Robocop, Its a DPMS SASS barrel that was 24 inches, bought it from Numrich for $120 and had it cut it to 16 inches and lightened the profile. The Gunsmith opened it up but I don't think it was enough or maybe my gas block is bottle neck. Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted March 9, 2015 Report Share Posted March 9, 2015 Robocop, Its a DPMS SASS barrel that was 24 inches, bought it from Numrich for $120 and had it cut it to 16 inches and lightened the profile. The Gunsmith opened it up but I don't think it was enough or maybe my gas block is bottle neck. This is good info to put out up front to help us diagnose the issues your having. Quote Link to comment Share on other sites More sharing options...
Modo Posted March 9, 2015 Author Report Share Posted March 9, 2015 true, I ordered a Seekins adjustable gas block. Hoping that cures the short stroking, if not im going to have the barrel port opened up. Im thinking of going 0.1095 cause I can always dial it down with the gas block, and can shoot anything no matter how anemic the round is. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted March 9, 2015 Report Share Posted March 9, 2015 You need to post this in the DPMS Technical section or General Section , Thanks . Agreed. Thanks. -Robo Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted March 9, 2015 Report Share Posted March 9, 2015 @Modo I have a 17" rifle-length barrel. The gas port was opened up to .099 The port inside of your GB can be as large as .125, so opening up to near that size and then adding an adjustable GB should be perfectly safe. When you had the barrel re-contoured, did you have the area at the gas block redone as well. If memory serves me right, the DPMS SASS has a canted surface at the gas block, and requires a SASS specific gas block. You may have to have that area also redone, perhaps down to a .750, to fit a standard fitting GB. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted March 9, 2015 Report Share Posted March 9, 2015 (edited) Ya, its tapered or something , there is a thread on it some where here . Unless that part of the barrel was untouched . I think the 24 " Barrel will have a smaller gas port than a 16" , there's a lot of Barrel after the port on a 24 ". although, was it opened up enough , that's a good question . You may also check some basic things also , enough Lubricant on new build ? DPMS Chambers were notorious for having rough or tight chambers also. Head space been checked ? As has been asked what stock system & its components , all 308AR ? Could also be bolt bounce , maybe the port is too large ? Does the BCG, hold open on last round ? Try it with one round in the mag & progress to three & see if it holds the Bolt back each test . Have you tried different manufacturers Magazines ? Edited March 9, 2015 by survivalshop Quote Link to comment Share on other sites More sharing options...
Modo Posted March 9, 2015 Author Report Share Posted March 9, 2015 First off, thanks for starting a thread/moving the posts. I confirmed that it's the correct rifle length buffer and spring. Buffer is 5.33oz and the spring is 39 coils and 12.75 inches. I saw that Fulton opens the port to 0.1095 on the 16 inch rifle length barrels. What number drill bit is that? Link to one one Amazon? Quote Link to comment Share on other sites More sharing options...
survivalshop Posted March 9, 2015 Report Share Posted March 9, 2015 I have to look up what drill bit size my 16" is . Its in a thread on this forum , some where & I have it written some where in my notes , but it may take me a bit to find it . Quote Link to comment Share on other sites More sharing options...
Modo Posted March 9, 2015 Author Report Share Posted March 9, 2015 I ran it wet, the bolt holds open on one round. ran 20 rounds of 147 grain ZQI 762 I got from Walmart. First I put one round in the PMAG and it fired and bolt locked open. I put 3 rounds and fired, round one fired but bolt came back and closed on the spent case. Had to pull the charging handle to eject the spent case and chamber the next round. With the ZQI this was the case with every round. Next I ran 10 rounds of Winchester 150 grain 308 I picked up oaktrees rifle range. One of the guys shooting there said that the ZQI is underpowered, and try something else. I put three rounds of the Winchester in the PMAG. Fired the first round and it shot fine, spent case flopped out right next to me on the table but it didn't pick up the next round. I had to pull the charging handle to load a live round. This happened with all 10 Winchester rounds. I'm running a 16 inch barrel with rifle length gas, and a fixed gas tube. When Randal was doing the assembly he drilled the gas hole, maybe it needs to be bigger?? Thoughts? Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted March 9, 2015 Report Share Posted March 9, 2015 7/64" = .1094 I wouldn't be afraid of going to the larger hole Quote Link to comment Share on other sites More sharing options...
Modo Posted March 9, 2015 Author Report Share Posted March 9, 2015 Sounds great. Off to Home Depot Quote Link to comment Share on other sites More sharing options...
FaRKle! Posted March 9, 2015 Report Share Posted March 9, 2015 (edited) When Randal was doing the assembly he drilled the gas hole, maybe it needs to be bigger??AR15barrels.com Randal(l)?How's the gas block mounted? Clamp on or set screw? Are there signs of leakage? Have you tried checking the gas block for fit and alignment?Another thing you can try is using a muzzle device that creates some back pressure so that the system (barrel + muzzle device) has the dwell time of a longer barrel. The Griffin Flash Comp and Bad-Ass Battle Comp do this. Edited March 9, 2015 by FaRKle! Quote Link to comment Share on other sites More sharing options...
Modo Posted March 9, 2015 Author Report Share Posted March 9, 2015 AR15barrels.com Randal(l)?How's the gas block mounted? Clamp on or set screw? Are there signs of leakage? Have you tried checking the gas block for fit and alignment?Another thing you can try is using a muzzle device that creates some back pressure so that the system (barrel + muzzle device) has the dwell time of a longer barrel. The Griffin Flash Comp and Bad-Ass Battle Comp do this. Yes AR15barrels Randall. Awesome guy, great watching him work. He even mentioned that I would probably need an adjustable gas block. I checked the block and alignment and it was dead on with no leaks. It's a set screw model, it was $24 ar15/10 model in 0.750 so it fit. Maybe that's the culprit. I have a ferfrans CQB brake and attachment, Quote Link to comment Share on other sites More sharing options...
98Z5V Posted March 10, 2015 Report Share Posted March 10, 2015 ran 20 rounds of 147 grain ZQI 762 I got from Walmart. First I put one round in the PMAG and it fired and bolt locked open... ...One of the guys shooting there said that the ZQI is underpowered, and try something else. Those two statements don't make any sense, and you proved it. "One of the guys shooting there" is wrong. If the ammo was underpowered, if wouldn't have locked the bolt back on one round. It's got enough power to cycle the rifle, or that test would have failed - and it didn't. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted March 10, 2015 Report Share Posted March 10, 2015 How does the fired brass look ? Any Scratches on the side of the brass , Extractor marks ? Inspect the chamber for roughness . Polish if necessary , one would think your Barrel guy would have checked all that , but you never know unless he said so . Quote Link to comment Share on other sites More sharing options...
EasyEJL Posted March 10, 2015 Report Share Posted March 10, 2015 my 308ar which has fed 40 year old south African and middle eastern surplus ammo fine can't manage to put 3 of those zqis downrange without some sort of horrible mishap. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted March 10, 2015 Report Share Posted March 10, 2015 If I remember correctly, Farkle bought some of that stuff. It ran horribly... But my 17" still ate it up. I have yet to have any serious ammo issues, despite having a rifle length gas system on a 17" barrel.... 17" may be the magic length. Quote Link to comment Share on other sites More sharing options...
guruofhotrod Posted March 10, 2015 Report Share Posted March 10, 2015 @Modo, I see in the Calguns Salt Works 308 build and review thread : http://www.calguns.net/calgunforum/showthread.php?t=1036853 that you have the new Salt Works 308 receiver set - how do you like it? I'm actually considering ordering the set since you can't beat the price not to mention that they look bad a$$ - you should post some pics for the guys here. I live in santa clarita but, I don't go to oaktree much, I prefer to go to "a place to shoot". My 308's are still "under construction" but, getting close - should be out plinking within the next month or so. Question, when your bolt locks open does the bolt carrier travel back far enough for the catch to engage with the bolt face or is it possibly catching on the forward edge of the carrier? Quote Link to comment Share on other sites More sharing options...
FaRKle! Posted March 10, 2015 Report Share Posted March 10, 2015 If I remember correctly, Farkle bought some of that stuff. It ran horribly... But my 17" still ate it up. I have yet to have any serious ammo issues, despite having a rifle length gas system on a 17" barrel.... 17" may be the magic length.Nope. I bought CBC/Magtech M80 ball. Awful stuff that's loaded HOT. I like their 5.56 loads though.My LMT MWS 16" rifle-gassed barrel runs well, though the CBC stuff still showed high pressure signs. Quote Link to comment Share on other sites More sharing options...
blue109 Posted March 10, 2015 Report Share Posted March 10, 2015 I ran through about 50 rds of ZQI no problem. my gun eats anything though. Quote Link to comment Share on other sites More sharing options...
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