Adjustable Gas Block - Need Recommendations

[Okie_Poke]

Hello all,

I'm upgrading my 6.5 Grendel this fall and plan to add an adjustable gas block when I switch barrels. I have a suppressor I plan to run on this rifle at times, though it will be shot both with and without a suppressor. I will be using an Aero Atlas S-One M-Lok handguard, which doesn't have the most room in it. The Aero website lists 1.3" inside diameter. I'm trying to confirm, but I think that's the horizontal ID and there is a bit more vertical ID due to the channel along the top. I think I've seen drawings of their dimensions before but I'm not seeing it on the website at the moment.

In any event, what adjustable gas blocks do you recommend? Aero has one that I know will work with their handguard, but I'm willing to pay a little more on this build if there is a better option. I haven't ordered the barrel yet, but I will likely have the option of choosing between a 1" or 1.92" gas block journal length. Even if you don't know if it will work with Aero's handguard, I'm interested in what adjustable gas blocks are recommended and why. I'm also interested in feedback on what not to buy and why.

Thank you in advance.

[grayfox]

The one by Aero has a nice feature in that the adjusting/setscrew is adjustable from the front, with a hex - about 3/32 I think, or so.. Plus you change it via series of clicks - 15 or so IIRC full open to full closed, I have a couple of them.
Use the hex key that has a ball at one end so you can tweak at a bit of an angle to the horizontal.
Lots of people on here swear by the SLR adjustables.
Also to consider is do you want to use the adjustable BCG - bootleg I think. only 4 clicks but lrrp52 uses it for his suppressed barrels.

The 1.3" that Aero has is pretty usual, I think it will also take their AGB too... otherwise why sell the 2 parts?

There is an Odin (I think), shiny SS but the tall part that sticks up into the top channel is a lot fatter than these others, so might not fit. I had one HG it would not fit into (not aero however).
I don't like AGB's where you can't get to the adjusting screw, some of them hide it under the side of the HG.

[Klem]

OP,

SLR recommends the set-screw model for handguards that are 1.3" ID. Their clamping style blocks need more ID.

SLR Sentry can be adjusted from the front with a 2mm ball driver and are reputable. No need to spend the extra dollars on a titanium version ($202) unless every last gram is critical to the build. The 4140 steel at $135 works just as well.

If you are using iron sights with those light-weight small diameter handguards be careful of flex. If you can see movement when you pinch the barrel and the handguard at the muzzle end then imagine what that will do to your zero.

[LRRPF52]

[Okie_Poke]

The one by Aero has a nice feature in that the adjusting/setscrew is adjustable from the front, with a hex - about 3/32 I think, or so.. Plus you change it via series of clicks - 15 or so IIRC full open to full closed, I have a couple of them.
Use the hex key that has a ball at one end so you can tweak at a bit of an angle to the horizontal.
Lots of people on here swear by the SLR adjustables.
Also to consider is do you want to use the adjustable BCG - bootleg I think. only 4 clicks but lrrp52 uses it for his suppressed barrels.

The 1.3" that Aero has is pretty usual, I think it will also take their AGB too... otherwise why sell the 2 parts?

There is an Odin (I think), shiny SS but the tall part that sticks up into the top channel is a lot fatter than these others, so might not fit. I had one HG it would not fit into (not aero however).
I don't like AGB's where you can't get to the adjusting screw, some of them hide it under the side of the HG.

Thank you.

[Okie_Poke]

OP,

SLR recommends the set-screw model for handguards that are 1.3" ID. Their clamping style blocks need more ID.

SLR Sentry can be adjusted from the front with a 2mm ball driver and are reputable. No need to spend the extra dollars on a titanium version ($202) unless every last gram is critical to the build. The 4140 steel at $135 works just as well.

If you are using iron sights with those light-weight small diameter handguards be careful of flex. If you can see movement when you pinch the barrel and the handguard at the muzzle end then imagine what that will do to your zero.

[Okie_Poke]

[Klem]

OP,

Here's the advice from SLR's website.

Note- If you have a barrel with no dimple or one dimple under the gas port either our .400 or .450 set screw spacing blocks will work fine. There is no difference in the blocks just the front set screw location.

So it depends on what barrel you decide to get. Some smiths drill one dimple, some two, and some none at all. Lilja machines a flat surface to aid lining up the gas port so with their barrels it's also a non-issue. These 0.400"/0.450" measurements only matter if you're getting a set-screw gas block AND the barrel has two dimples. If the barrel has two dimples, then you need to find out the distance between them get the appropriate gas block. That said, as long as you screw up the one nearest the shoulder first then it won't be a perfect match but should work fine.

As for whether an Adjustable carrier is any cleaner than an AGB, you won't notice the difference. This is because most suppressor soot comes directly from the chamber, not the gas system. I say this after using an Adams Arms piston where the gas system ends at the spigot out front near the block. No gas from the piston can come into the receiver. Yet with a suppressor the receiver would end up just as filthy as a gas impingement system. After firing it all spews back around the case into the receiver while still under pressure.

[LRRPF52]

[Okie_Poke]

[Okie_Poke]

OP,

Here's the advice from SLR's website.

Note- If you have a barrel with no dimple or one dimple under the gas port either our .400 or .450 set screw spacing blocks will work fine. There is no difference in the blocks just the front set screw location.

So it depends on what barrel you decide to get. Some smiths drill one dimple, some two, and some none at all. Lilja machines a flat surface to aid lining up the gas port so with their barrels it's also a non-issue. These 0.400"/0.450" measurements only matter if you're getting a set-screw gas block AND the barrel has two dimples. If the barrel has two dimples, then you need to find out the distance between them get the appropriate gas block. That said, as long as you screw up the one nearest the shoulder first then it won't be a perfect match but should work fine.

As for whether an Adjustable carrier is any cleaner than an AGB, you won't notice the difference. This is because most suppressor soot comes directly from the chamber, not the gas system. I say this after using an Adams Arms piston where the gas system ends at the spigot out front near the block. No gas from the piston can come into the receiver. Yet with a suppressor the receiver would end up just as filthy as a gas impingement system. After firing it all spews back around the case into the receiver while still under pressure.

[mtnlvr]

I have the clamp on SLR adjustable gas block under an M-LOK hand guard. I can reach the adjuster with a longer, standard end allen key even with my TBAC Ultra installed (a ball end would be a little nicer). The gas block is a snug fit under the hand guard. So much so, that I cannot install any M-LOK accessories in a couple of slots on the bottom. The clamp to hand guard clearance is about 0.055", maybe a smidge less clearance to the clamp screws. It's a dia 1.36" ID PSA hand guard.

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[montana]

The best adj gas block for high end builds is the Rifle Speed, it has no equal.

The caveat is it is expensive, requires a straight gas tube and requires a hand guard of adequate I.D. and length for proper fit..

The Rifle Speed needs no tools to adjust and uses different adjuster plungers lengths for different gas adjustment needs.. I custom fit my adjuster plunger by shortening it to the perfect length..I also added a second adjustment spring for extra resistance for adjustment..

The Rifle Speed can be easily pinned if desired.

Every adj gas block needs maintenance to prevent the adjuster from carbon freeze..The Rifle Speed is very easy to maintain, service and replace parts..

https://www.riflespeed.com/RIFLESPEED-Gas-Controls-750_p_12.html

[Jake TN]

Probably the most important thing you need to determine is if this a set and forget setup. Do you plan on changing loads frequently or shooting suppressed and unsuppressed? If you will make making changes frequently I would go with the superlative or buy once and cry once with rifle speed. If you are going to only shoot suppressed with the same ammo, then any decent adjustable gas block will do. I, nor my counterparts, have ever used an adjustable carrier so I cannot speak to that. Alternatively, buy a flow through suppressor and not worry about any of it.

[Okie_Poke]

I have the clamp on SLR adjustable gas block under an M-LOK hand guard. I can reach the adjuster with a longer, standard end allen key even with my TBAC Ultra installed (a ball end would be a little nicer). The gas block is a snug fit under the hand guard. So much so, that I cannot install any M-LOK accessories in a couple of slots on the bottom. The clamp to hand guard clearance is about 0.055", maybe a smidge less clearance to the clamp screws. It's a dia 1.36" ID PSA hand guard.

Thank you.

The best adj gas block for high end builds is the Rifle Speed, it has no equal.

The caveat is it is expensive, requires a straight gas tube and requires a hand guard of adequate I.D. and length for proper fit..

The Rifle Speed needs no tools to adjust and uses different adjuster plungers lengths for different gas adjustment needs.. I custom fit my adjuster plunger by shortening it to the perfect length..I also added a second adjustment spring for extra resistance for adjustment..

The Rifle Speed can be easily pinned if desired.

Every adj gas block needs maintenance to prevent the adjuster from carbon freeze. The Rifle Speed is very easy to maintain, service and replace parts..

https://www.riflespeed.com/RIFLESPEE...-750_p_12.html

I had not heard of this one previously (I'm new to adjustable gas blocks) but am looking into it. It's very interesting. I just need to figure out if it will work with what I'm trying to do.

Probably the most important thing you need to determine is if this a set and forget setup. Do you plan on changing loads frequently or shooting suppressed and unsuppressed? If you will make making changes frequently I would go with the superlative or buy once and cry once with rifle speed. If you are going to only shoot suppressed with the same ammo, then any decent adjustable gas block will do. I, nor my counterparts, have ever used an adjustable carrier so I cannot speak to that. Alternatively, buy a flow through suppressor and not worry about any of it.

I currently run a few different 123 grain bullets on top of CFE 223, but they are all basically the same load. And I run one of them way more than the others, so I think of myself as only really shooting one load in my current Grendel. I am hoping the new barrel will like similar loads as the old barrel, though I'll of course have to do some load work up. I plan to find loads for 123 match bullets and SSTs, barrel willing, and just shoot those for the most part. However, I do plan to switch back and forth between suppressed and not suppressed. One of the matches I shoot with my Grendel doesn't allow suppressors or muzzle brakes (only flash hiders). The other match allows suppressors, and I've grown fond of shooting suppressed whenever possible with my bolt guns when hunting or just shooting at the range. I'd like to think that will extend to this build.

Question: what about the superlative makes it better than some others for more frequent changes? I can see with the riflespeed you just turn it. But why would the superlative be better than, for example, the Aero or SLR (or is it)? Thank you!