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Baga
06-02-2012, 2:04 AM
I'm thinking of getting the Troy MRF-308 Handguard along with a DPMS SASS Barrel, what gas block do you recommend that will work with this setup?

rt7
06-02-2012, 5:18 AM
I believe you only have 3 choices, the dpms proprietary gas block, PRI makes one ans JSE sells a lo pro gas block for the SASS.

baih777
06-02-2012, 5:28 AM
I would buy the DPMS gas block. attached is a pic of a bull barrel gas block. the 4 rail was suppose to be for a .308. the other is from DPMS. notice the gas port is a different height.
i am using a DPMS ss fluted bull 24 inch and a 18 inch SASS bull barrel.

SR-71 BLACKBIRD
06-02-2012, 6:35 AM
While doing my research on that barrel, I want to say the best gas block recommended was the low profile block from DPMS. It's expensive, but I have had no issues with it thus far. Side note, it does not come with the roll pin, so you have to buy that separately.

SASS Low Profile gas block (http://www.midwayusa.com/product/274547/dpms-sass-low-profile-ar-15-lr-308-bull-barrel-936-inside-diameter-steel-matte)

baih777
06-02-2012, 7:19 AM
i am using this one.
http://www.jsesurplus.com/dpmsmicro936gasblock.aspx

it looks like its thinner.

FMJBT
06-02-2012, 7:39 AM
I'd go with the SASS gas block from DPMS. It's pricey, but the barrel is already dimpled for it, and it's a bit longer than a standard low profile gas block so it has a bit more sealing surface against the barrel as well as 3 set screws instead of the 2 set screws on the low profile (More clamping force). The mid length gas system on the SASS barrel is bleeding off gas while it's still pretty high pressure, so having that extra sealing surface will help prevent or at least minimize gas leaks at the block. I've noticed very minimal gas leak-by at the block on my SASS barreled 308.

The low profile block sold by JSE Surplus (Also made by DPMS) would be my next choice. It's a lot cheaper, but still pretty high quality. I'm running one of those on my 26" Armalite based AR-10, which has a similar barrel profile as the SASS (1.125" under the handguards).

That's pretty much it for gas blocks that will fit under a handguard. The JP adjustable block is railed on top, so it would only work with a shorter mid length handguard. One other option that might work, especially if you ever plan on running a suppressor, is the low profile 3 position gas block made by Paladin Machine Services. They make each block individually to fit you barrel and gas system, so it would be custom fit to clear the heavy barrel. It's not adjustable in the same sense as the JP unit, you can't really tune it to make your gun run smoother. The 3 positions are High (Fully open, runs like a standard gas block), Low (Smaller orifice for suppressed use, pushes less gas into the receiver to compensate for the extra pressure caused by running a can), and Cut-Off (Disables gas system, makes the gun run single shot like a bolt action).

I'm also running the Troy 13.8" MRF on my 308 build. I'm honestly wishing I had gone another route on that part of the build. I was initially pretty happy with it, but last time I took it out I noticed that it was shifting as I fired. Not much, but enough to notice that the clearance below the scope bell was getting smaller. The weight of the rifle sitting on the bipod, combined with recoil is making the forend tilt upwards at the end, so the railed surface is no longer parallel with the rail on the receiver. It almost looks like I have a 20MOA sloped receiver, but it's not. I've taken it off, inspected, cleaned, re-installed a few times now and it always ends up doing the same thing. The design itself does not really inspire confidence in it's ability to stay aligned with the receiver. The clamping setup is basically just a big scope ring at the back that the rest of the 13.8" handguard hinges against. If I had it to do over again, I'd probably go with the JP handguard or some other design that uses an externally threaded barrel nut to attach the forend.

http://farm7.staticflickr.com/6099/6232869625_e961031bd7_z.jpg

Baga
06-02-2012, 5:04 PM
i am using this one.
http://www.jsesurplus.com/dpmsmicro936gasblock.aspx

it looks like its thinner.

I was looking at this one as well. Anyone know the difference between this gas block ($17 DPMS) and the expensive one ($99 DPMS)?

Baga
06-02-2012, 5:06 PM
I'd go with the SASS gas block from DPMS. It's pricey, but the barrel is already dimpled for it, and it's a bit longer than a standard low profile gas block so it has a bit more sealing surface against the barrel as well as 3 set screws instead of the 2 set screws on the low profile (More clamping force). The mid length gas system on the SASS barrel is bleeding off gas while it's still pretty high pressure, so having that extra sealing surface will help prevent or at least minimize gas leaks at the block. I've noticed very minimal gas leak-by at the block on my SASS barreled 308.

The low profile block sold by JSE Surplus (Also made by DPMS) would be my next choice. It's a lot cheaper, but still pretty high quality. I'm running one of those on my 26" Armalite based AR-10, which has a similar barrel profile as the SASS (1.125" under the handguards).

That's pretty much it for gas blocks that will fit under a handguard. The JP adjustable block is railed on top, so it would only work with a shorter mid length handguard. One other option that might work, especially if you ever plan on running a suppressor, is the low profile 3 position gas block made by Paladin Machine Services. They make each block individually to fit you barrel and gas system, so it would be custom fit to clear the heavy barrel. It's not adjustable in the same sense as the JP unit, you can't really tune it to make your gun run smoother. The 3 positions are High (Fully open, runs like a standard gas block), Low (Smaller orifice for suppressed use, pushes less gas into the receiver to compensate for the extra pressure caused by running a can), and Cut-Off (Disables gas system, makes the gun run single shot like a bolt action).

I'm also running the Troy 13.8" MRF on my 308 build. I'm honestly wishing I had gone another route on that part of the build. I was initially pretty happy with it, but last time I took it out I noticed that it was shifting as I fired. Not much, but enough to notice that the clearance below the scope bell was getting smaller. The weight of the rifle sitting on the bipod, combined with recoil is making the forend tilt upwards at the end, so the railed surface is no longer parallel with the rail on the receiver. It almost looks like I have a 20MOA sloped receiver, but it's not. I've taken it off, inspected, cleaned, re-installed a few times now and it always ends up doing the same thing. The design itself does not really inspire confidence in it's ability to stay aligned with the receiver. The clamping setup is basically just a big scope ring at the back that the rest of the 13.8" handguard hinges against. If I had it to do over again, I'd probably go with the JP handguard or some other design that uses an externally threaded barrel nut to attach the forend.

http://farm7.staticflickr.com/6099/6232869625_e961031bd7_z.jpg

Thanks for the info. Awesome FDE 308 setup...What kind of grip is that? I know Ergo has one like that but the plam support is black instead of all FDE.

FMJBT
06-02-2012, 5:21 PM
Thanks for the info. Awesome FDE 308 setup...What kind of grip is that? I know Ergo has one like that but the plam support is black instead of all FDE.

It's Ergo. I think the newer production versions might have the black palm shelf. I bought mine a few years ago. I think you'll like the SASS barrel, regardless of which gas block you go with. Shooting decent ammo, they will keep up with just about any bolt gun short of the high end precision rifles. Mine will group 190 Sierra Match Kings into about 1/2 to 3/4 moa on most days.