Scott G Posted August 24, 2014 Report Share Posted August 24, 2014 I've seen several threads saying there is no difference in the .223 gas blocks and the .308. However I just got off the Precision Reflex website and they have two different adjustable gas blocks for barrels with .875" OD, which is what I need. They are out of the one they advertise for .308 (item 03-875-02GT) but they have "ample stock" for the one made for the AR-15 (item 05-875-02GT). Does anyone know what the difference in the two would be? They appear to be identical with the exception of one supposedly made for the AR-15 and the other for .308. Quote Link to comment Share on other sites More sharing options...
j.peace Posted August 24, 2014 Report Share Posted August 24, 2014 Gas block size relates more to the profile of your barrel . but I'm not sure about the specifics. Hang in there other more knowledgeable members will be along shortly Quote Link to comment Share on other sites More sharing options...
98Z5V Posted August 24, 2014 Report Share Posted August 24, 2014 Gas port diameter on the two, the one in the block. Larger port on the 308 version, but it won't matter if you use the 15 version. As it is, the port is drilled larger than the largest rifle barrel gas port. The 15 version will still run that 308 with ease. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted August 24, 2014 Report Share Posted August 24, 2014 Could also be some adjustably range difference between the two. Quote Link to comment Share on other sites More sharing options...
warthog984 Posted August 24, 2014 Report Share Posted August 24, 2014 It looks like the PRI will not fit under most hand guards per the note on their website. I put a SLR Rifleworks adjustable gas block on mine. It is very small. Also, the SLR adjusts from the front rather the side. Makes it easier to adjust the gas with the a long allen key. Quote Link to comment Share on other sites More sharing options...
Scott G Posted August 24, 2014 Author Report Share Posted August 24, 2014 I'm using a JP free float hand guard and the Precision Reflex gas block will fit and I can even access the gas adjustment screw easily through the slots on the handguard. I know this because it has a .936" under the rail already. I just bought this rifle from a local guy instead of building one myself because he used all premium parts (except for the trigger) and I bought it for less than the sum of the parts. Problem is, for whatever reason, he put the .936" gas block on the .875" barrel and just snugged it up with the set screws. My bad for not checking it closer before buying it I suppose. He marred the barrel up pretty good too by overtightening the set screws to compensate for using the wrong size. Crap! Having said all that, I just looked at the SLR that Warthog suggested and really like the way it's designed. I like the idea of being able to shut the gas port to the fully closed position while cleaning and then being able to open it back to the exact same spot. Too bad they cost $55 more than the Precision Reflex, but I'm going with the SLR anyway. Thanks to everyone who posted here, I really appreciate the feedback. Quote Link to comment Share on other sites More sharing options...
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