20" Barrel, Adjustable gas block needed?

[hdrolling]

So reading through different threads and using the search feature I'm undecided if an adjustable gas block is going to be "needed" in my build.

So i'll try to spell out my thoughts.

For my 20" build (using the 20" Faxon GB barrel) I would prefer a non-adjustable gas block so I can use a 15" or longer free float hand guard.
Could you also comment on why you decided to go with an adjustable ie. suppressor, different bullet loads etc.
And if you could post what length hand guard you used to be able to adjust the gas block (rifle length gas system only). I see places sell long allen head tools for what I'm guessing is for owners with longer hand guards?

I'm looking at a good clamp on non-adjustable gas block but before I order one and a longer hand guard I want to make sure there is no reason I "need" an adjustable.

Also it looks like the SRL sentry 7 is a go to for many that use adjustable's, are these easy to adjust with a 15" or 16.5" hand guard?

Pics of either installed would be helpful, on the picture thread not everyone lists if their using an adjustable or not.

Thanks

[Kilco]

If it's a 20" barrel with a RLGS and a .94 port, I believe they run very well without an adjustable gas block.

I have no experiences with suppressors so ill leave that to the more knowing folk.

[VASCAR2]

I put an adjustable gas block on my 20" Shilen and haven't had to adjust it since my first day I set it on the range. The only way I'll put an adjustable gas block on another 20" 6.5 Grendel is if I was going to use a suppressor. Since I live in Illinois suppressors are not currently an option. I seriously considered getting a 20" Faxon group buy barrel and would've used a standard low progile gas block. I used a 15" Hogue over molded free float hand guard on my 20" Shilen barrel. I used a JP adjustable gas block clamp on with a top Picatinney rail.

[Wafavre2]

20" Bartlein PF with RLGB, SLR adjustable Gas Block with a Lancer Rifle+ Carbon Fiber hand guard. SLR came with the longer Allen Wrench. Setup GB with Wolf Steel cased to cycle and did not have to readjust with factory or handloads. I plan on using a suppressor so I installed the adjustable. Another advantage to an adjustable GB is you can tune it to the buffer system as needed and change from carbine to Rifle. Install an adjustable once and have flexibility.

Will

[Kswhitetails]

If you have an adjustable GB, you can turn off your gas. Then you have a gas-less gas gun!

I had a seekins GB inside my 15" NOXS rail. Worked like a champ. I never had to tune it down, ran it wide open. It was a freebie with the guard, and I didn't yet have a suppressor, so no need.
20" with RLGS and a .09x port.

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This was an experimental install of my SLR HELIX 16". Looked great, and I could easily enough adjust it inside the guard. Be advised, obtain a long allen socket to adjust the set screw or adjustment screw if they are accessed from the front of the hand guard. My two cents.

[cb4017]

So far I haven't found that a 6.5 Grendel needs an adjustable gas block, if the gas port is properly sized. I've built two 20" uppers and just received a LaRue 18" upper. All run fine and are well behaved without an adjustable gas block.

[hdrolling]

Well I decided since I don't have a suppressor yet to just go with a low profile non-adjustable GB.

Started ordering this months parts:

20" Faxon barrel via the group buy
"Monster" bolt via the group buy
Sionics NP3 coated bolt carrier w/ firing pin, NP3 coated cam pin and firing pin retaining pin
Noveske marked VLTOR MUR upper with forward assist
Noveske 16.5" NSR handguard
Noveske low pro gas block
Black WMD rifle length gas tube
x3 E lander mags

I already have a BCM comp mod 1 that I removed from my 300 blk than I plan to use for now.

If all these parts come in before I get paid again I use the lower off my DDM4V11 PRO that already has a PRS stock and Geissele SSA-E trigger in it to go test the upper out.

[RogueNathan]

You should not need an adjustable for the vast majority of loads. We used the gas port spec'd by Bill Alexander.

However, an adjustable can always help reduce recoil assuming your load has extra energy to support reducing the gas port diameter.

[hdrolling]

You should not need an adjustable for the vast majority of loads. We used the gas port spec'd by Bill Alexander.

However, an adjustable can always help reduce recoil assuming your load has extra energy to support reducing the gas port diameter.

I'm going to see how the non-adjustable works out, normally I just use one load and target practice with that. The longest range we have here in the FT Bragg area is 600 yards so that's going to be my target range.

[hdrolling]

And just like that I have an SLR Sentry 7, since I've never used one I really want to try one out. I was worried it wouldn't it wouldn't fit under my hand guard but now that I have it it's almost the same size as my low profile noveske gas block.

Won't know for sure until I get my barrel but I'll be ready for when it gets here.

[sawacs]

So reading through different threads and using the search feature I'm undecided if an adjustable gas block is going to be "needed" in my build.

So i'll try to spell out my thoughts.

For my 20" build (using the 20" Faxon GB barrel) I would prefer a non-adjustable gas block so I can use a 15" or longer free float hand guard.
Could you also comment on why you decided to go with an adjustable ie. suppressor, different bullet loads etc.
And if you could post what length hand guard you used to be able to adjust the gas block (rifle length gas system only). I see places sell long allen head tools for what I'm guessing is for owners with longer hand guards?

I'm looking at a good clamp on non-adjustable gas block but before I order one and a longer hand guard I want to make sure there is no reason I "need" an adjustable.

Also it looks like the SRL sentry 7 is a go to for many that use adjustable's, are these easy to adjust with a 15" or 16.5" hand guard?

Pics of either installed would be helpful, on the picture thread not everyone lists if their using an adjustable or not.

Thanks

After running an adjustable gas block, I wondered why I had not installed one sooner!

I run the SLR Sentry 7, set screw variant, on two 6.8's (16" and 18"), a 223 wylde, and a soon to be completed 6mm Predator (Grendel based).

With the adjustable gas block, I can tune the rifle to eject the rounds where they should be ejecting and keep a large portion, if not most, of the blowback from the suppressor out of the receiver. If I want to keep my brass looking like it came out of a bolt action rifle, I can close the gas block off enough to break the case free from the chamber but not eject the case leaving me to manually cycle the bolt. Shooting this way works great for loading out past mag length for accuracy testing.

Regarding adjusting the gas block, SLR makes an extended ball driver that allows you to reach the adjustment screw. For example, I can adjust the gas block while running the SLR 16" SOLO rail with a mid-length gas system and can still reach the same gas block with the 16.5" SOLO rail.

The pic is a 18" 6.8 with a mid-length gas system running the SLR Sentry 7 and 16" SOLO rail. Adjusting the gas block is no problem with this tool: http://slrrifleworks.com/index.php?route...duct_id=75



Hope this helps,

Sawacs

[hdrolling]

After running an adjustable gas block, I wondered why I had not installed one sooner!

I run the SLR Sentry 7, set screw variant, on two 6.8's (16" and 18"), a 223 wylde, and a soon to be completed 6mm Predator (Grendel based).

With the adjustable gas block, I can tune the rifle to eject the rounds where they should be ejecting and keep a large portion, if not most, of the blowback from the suppressor out of the receiver. If I want to keep my brass looking like it came out of a bolt action rifle, I can close the gas block off enough to break the case free from the chamber but not eject the case leaving me to manually cycle the bolt. Shooting this way works great for loading out past mag length for accuracy testing.

Regarding adjusting the gas block, SLR makes an extended ball driver that allows you to reach the adjustment screw. For example, I can adjust the gas block while running the SLR 16" SOLO rail with a mid-length gas system and can still reach the same gas block with the 16.5" SOLO rail.

The pic is a 18" 6.8 with a mid-length gas system running the SLR Sentry 7 and 16" SOLO rail. Adjusting the gas block is no problem with this tool: http://slrrifleworks.com/index.php?route...duct_id=75


Hope this helps,

Sawacs

Thanks, my only concern is that the SLR sentry 7 wouldn't fit under my Noveske NSR hand guard. While researching I came across a few threads where owners had gas bock hitting the NSR and they needed to change to smaller gas blocks.

Now that I have the Noveske low profile GB and the Sentry 7 they look very close in size. But until I get my barrel and mock up with the gas block and hand guard I won't know for sure if it will clear the hand guard.

IMG_8992 by IMG_8995 (1) by hd_rolling, on Flickrhd_rolling, on Flickr

[Kswhitetails]

Do you have another barrel to scavenge and use? Seems like it'd be simple enough to slide on a GB, and test fit a barrel, caliber wouldn't make a difference on ODs. It won't be worth dis-mantling another weapon, but the way you seem to have extras... never know, you may have 4 barrels leaning in the corner

[hdrolling]

Do you have another barrel to scavenge and use? Seems like it'd be simple enough to slide on a GB, and test fit a barrel, caliber wouldn't make a difference on ODs. It won't be worth dis-mantling another weapon, but the way you seem to have extras... never know, you may have 4 barrels leaning in the corner

No extra barrels, and all my current uppers are factory assembled so I don't want to take any apart. I already have the two gas blocks and I know the Noveske non adjustable fits so I'm 99% sure the SLR will, and I have a good feeling we'll be getting our 20" group buy barrels really soon now that the 12" barrels are done and mailed out.

[grayfox]

Seeing the pictures, I'd definitely wait for the 'proof of the pudding'...
If you line up the exposed setscrews with the bottom of the plain one, the height dimension seems significant... under a handguard that is...
:confused:

[hdrolling]

Seeing the pictures, I'd definitely wait for the 'proof of the pudding'...
If you line up the exposed setscrews with the bottom of the plain one, the height dimension seems significant... under a handguard that is...
:confused:

Hopefully the set screws won't be exposed, I have an SLR set screw jig so I can dimple the barrel for a more secure fit. I'm guessing now that all the 12" group buy barrels are in and shipped out that the 20" barrels will soon follow.

[Gman6.5]

I just built a 20" Faxon barreled with a Faxon non adjustable LP GB and it ran like a thief with Hornady Black, and SST 123's. Also has a spikes T-1 buffer similar to a carbine weight buffer.

I think my Faxon liked the SST's better!

[Gman6.5]

I originally had BCM KMR Alpha rail (1.3 inner diameter) on my build that I believe the low-profile Faxon GB was vibrating against the rail giving me vertical stringing and as soon as I replaced it with a MI SP-Series (Suppressor Compatible) Rail the vertical stringing went away I am now getting good groups.

At first I thought there would be no problem because it did clear by a bit when looking at it inside the rail. When just flexing the barrel by hand it seemed to flex a lot more with the BCM KMR Alpha than it does with the larger more sturdy barrel nut of MI.

I also noticed with a couple of BCM KMR rails I used in the past it seemed that the barrel nut is made of a soft metal and marred very easy even when only torquing to 40 foot-pounds as per instructions from BCM.

When I installed the MI rail I went with Bill Alexander's advice and didn't want to torque any less than 60 foot-pounds and ended up making it to almost 80 foot-pounds when everything lined up and that seemed to do the trick.

[sawacs]

Hdrolling, good luck with the gas block and the build.

For what its worth, I had to grind a little from the SOLO rail to be certain the gas block would not rub the rail. The S7 gas block was just too close for my comfort zone

[hdrolling]

Hdrolling, good luck with the gas block and the build.

For what its worth, I had to grind a little from the SOLO rail to be certain the gas block would not rub the rail. The S7 gas block was just too close for my comfort zone

Hmm, looks like the SOLO and NSR are both 1.3 inner diameter. That doesn't sound to promising, is the grinding noticeable from the outside?