jtallen83 Posted March 15, 2017 Report Share Posted March 15, 2017 I picked up one of the fairly new Superlative Arms DI adjustable gas blocks for use on my Matrix 308 AR build while suppressed. https://suparms.com/collections/adjustable-gas-blocks-direct-impingement Took it to the range today thinking I would adjust it on the "bleed off" setting for use with my SDN-6 suppressor. With 175 gr match ammo I adjusted it as far as it would go and never got the failure to lock back you are supposed to reach. The only ammo I had that would not lock back at this max setting was ZQ and Perfecta. They both locked back after just one click closed. Makes me think these blocks are not really intended for 308 AR's in the bleed off mode. In the restricted mode it functioned like you would expect, 4 clicks open from the closed position and the bolt locks back when running suppressed. Another side effect of running in the bleed off mode was the finish on the exposed corner of my suppressor started coming off, must have been thin on the corner to begin with. The adjustment system takes some getting used to. There are 4 clicks for every full rotation of the screw. From screwed down tight to 4 1/2 turns out it acts like the standard restrictive flow gas block. At the 4 1/2 turns it is wide open like a normal gas block. As you continue to turn the screw out it starts to bleed off more and more gas. The pictures here show the screw one click in from the max bleed off setting. I may just swap it around and give it a try on one of my 5.56 rifles running suppressed. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted March 16, 2017 Report Share Posted March 16, 2017 Contact them & ask them that question . Is this one of the Barrels you had to open up the Barrels Gas Port ? Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted March 16, 2017 Author Report Share Posted March 16, 2017 16 minutes ago, survivalshop said: Contact them & ask them that question . Is this one of the Barrels you had to open up the Barrels Gas Port ? Yep, 16 inch rifle gas might have something to do with it. It was opened up one size at a time till it functioned with the cheaper ammo. No need to ask them, "The Superlative Arms patented “Bleed Off”, direct impingement, gas block for the AR15 platform adjusts the gas flow by bleeding the gas out of the block instead of restricting the flow like conventional adjustable blocks. " I was just hoping like most adjustable blocks it would work for the big brother, it does actually work for the 308 just not the bleed off portion of the system, only in the standard restrictive mode. I'm thinking the 308 just has so much more gas volume it would take a much larger bleed off port to make enough difference. Quote Link to comment Share on other sites More sharing options...
dpete Posted March 16, 2017 Report Share Posted March 16, 2017 I have one on my 300BLK SBR with an 8" barrel and so far it has worked great. I run it strictly suppressed and have it set to bleed off excess gas 26 clicks from fully closed when shooting 220-225 grain subs. I haven't tried restricting gas yet for shooting supers. Closed to 4 1/4 turns(17 clicks) is restricted zone. 4 1/2 turns(18 clicks) is fully open. 19-32 clicks is fully open + bleed off mode Quote Link to comment Share on other sites More sharing options...
survivalshop Posted March 16, 2017 Report Share Posted March 16, 2017 7 hours ago, jtallen83 said: I'm thinking the 308 just has so much more gas volume it would take a much larger bleed off port to make enough difference. Your probably more then correct with that assessment . I would still contact them , maybe they have something in the works or can alter your for use in a 308 powered rifle . Quote Link to comment Share on other sites More sharing options...
pyzik Posted March 16, 2017 Report Share Posted March 16, 2017 Hmm. I was planning on one of these for my build. I'll have to double check the gas length on my 16" barrel (got is second hand and don't recall the gas length). I was thinking this GB would offer the most adjustibility for tuning the rifle. Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted March 17, 2017 Author Report Share Posted March 17, 2017 8 hours ago, pyzik said: Hmm. I was planning on one of these for my build. I'll have to double check the gas length on my 16" barrel (got is second hand and don't recall the gas length). I was thinking this GB would offer the most adjustibility for tuning the rifle. It works fine in the restrictive mode but I would think my 16 inch rifle length gas would be about as tame as a 308AR can get as far as gas impulse. It may also be that running suppressed changes things enough to prevent the bleed off mode from working, I have not tried it without the suppressor but really don't find the need to since I fully intend on running suppressed all the time. It's looking like a standard restrictive adjustable block would perform the same. Quote Link to comment Share on other sites More sharing options...
pyzik Posted March 17, 2017 Report Share Posted March 17, 2017 5 minutes ago, jtallen83 said: It works fine in the restrictive mode but I would think my 16 inch rifle length gas would be about as tame as a 308AR can get as far as gas impulse. It may also be that running suppressed changes things enough to prevent the bleed off mode from working, I have not tried it without the suppressor but really don't find the need to since I fully intend on running suppressed all the time. It's looking like a standard restrictive adjustable block would perform the same. My main concern is just making sure it cycles properly. I've read it's just a good idea to have an adjustable gas block. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted March 17, 2017 Report Share Posted March 17, 2017 10 hours ago, pyzik said: My main concern is just making sure it cycles properly. I've read it's just a good idea to have an adjustable gas block. I don't run any adj. gas blocks ,308AR's or AR 15's , the only one thats has adjustability is my Superlative Piston system AR 15 & that came that way , not that it needed it , but I don't run any Suppressed , that is a different ball game . They are not needed for action function , seems what I read ,most want them for reduced recoil , which in doing so can cause other issues . I could write a Chapter here on the pro's & Con's of them or the reasons why you might need one . Quote Link to comment Share on other sites More sharing options...
pyzik Posted March 17, 2017 Report Share Posted March 17, 2017 36 minutes ago, survivalshop said: I don't run any adj. gas blocks ,308AR's or AR 15's , the only one thats has adjustability is my Superlative Piston system AR 15 & that came that way , not that it needed it , but I don't run any Suppressed , that is a different ball game . They are not needed for action function , seems what I read ,most want them for reduced recoil , which in doing so can cause other issues . I could write a Chapter here on the pro's & Con's of them or the reasons why you might need one . Ah, understood. I thought people were using them to tune the rifle. It's a .308, the retail can't be THAT bad can it? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted March 17, 2017 Report Share Posted March 17, 2017 2 hours ago, pyzik said: It's a .308, the retail can't be THAT bad can it? The recoil isn't bad - much better on the .308ARs than on a .308 Win bolt gun. Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted May 23, 2017 Author Report Share Posted May 23, 2017 Just hit 300 rounds on the Superlative gas block. Never did get a reply from the company about 308AR use. Once I catch a good sale on SLR's this will get moved to the 300BO or a 5.56. I can't get enough bleed off to slow down the bolt enough. No malfunctions but it is really beating up the brass bad, mostly putting a crimp in the mouth, ejects to around 2 o'clock. here are a few pics showing how dirty things get, forgot to get a shot of the powder burn on the back of the suppressor, makes her a dirty girl from front to back. Quote Link to comment Share on other sites More sharing options...
Steve L Posted September 4, 2017 Report Share Posted September 4, 2017 On 3/17/2017 at 5:56 AM, survivalshop said: I don't run any adj. gas blocks ,308AR's or AR 15's , the only one thats has adjustability is my Superlative Piston system AR 15 & that came that way , not that it needed it , but I don't run any Suppressed , that is a different ball game . They are not needed for action function , seems what I read ,most want them for reduced recoil , which in doing so can cause other issues . I could write a Chapter here on the pro's & Con's of them or the reasons why you might need one . I purchased an adjustable gas based on hearing that 308 ARs were known to be over-gassed. This too has been my experience with my 308. I was having my rifle attempting to extract the casing before the casing had time to cool/shrink. This was a timing issue that the adjustable gas block cured. Given my experience is limited and I have a lot to learn yet. Dialing back the pressure has made the difference plus my brass no longer has ejector marks. FWIW: Hornady markets their Superperformance ammunition as a solution for over-gassed ARs. Link - https://www.hornady.com/support/superformance-in-gas-operated-firearms Quote Link to comment Share on other sites More sharing options...
mineralman55 Posted September 5, 2017 Report Share Posted September 5, 2017 Well, Hornady has certainly modified their official line on the SuperPerformance ammo. A few years ago I had some correspondence with them about using SuperPerformance ammo in M14 and M1 type rifles. Their answer was it is not for gas rifles, period. Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted September 5, 2017 Report Share Posted September 5, 2017 SLR Sentry. That's all you need to know. Quote Link to comment Share on other sites More sharing options...
First Sergeant Posted September 6, 2017 Report Share Posted September 6, 2017 On 9/4/2017 at 4:56 PM, Steve L said: I purchased an adjustable gas based on hearing that 308 ARs were known to be over-gassed. This too has been my experience with my 308. I was having my rifle attempting to extract the casing before the casing had time to cool/shrink. This was a timing issue that the adjustable gas block cured. Given my experience is limited and I have a lot to learn yet. Dialing back the pressure has made the difference plus my brass no longer has ejector marks. FWIW: Hornady markets their Superperformance ammunition as a solution for over-gassed ARs. Link - https://www.hornady.com/support/superformance-in-gas-operated-firearms Kind of had same issue brass was beat to sheet ejecting hard at 1 o'clock the MT / live sort of double feed Was a last resort of sorts. If it came push to shove, I keep an Allen wrench on board and would open it up and let it eat. Quote Link to comment Share on other sites More sharing options...
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