Hand-guard and Barrel Length for gas block

[thirstman]

Hey fellas,

I am trying to figure out if I'll be able to utilize this gas block properly with the parts in the build I'm going for before I buy them.

I got the following parts:

Aero Precision M5 Builder Set w/ ATLAS S-ONE Handguard

JP Rifles 22" Super Match Barrel

Seekins Precision SELECT ADJUSTABLE GAS BLOCK

So how can I reasonably figure out how far down the barrel where the gas block will sit, and how far down the hand-guard will cover?

 

[thirstman]

I just realized this gas block doesn't come in .875 diameter. So I guess this thread is two points, I need to find an adjustable gas block that has an easy tool-free adjustment after I figure out how to measure.

I have edited the above post with a different gas block

 

[Snuby642]

17 inch handgaurd I think,
15 is normal rifle lenght.

 

[Milf Dots]

Hey fellas,

I am trying to figure out if I'll be able to utilize this gas block properly with the parts in the build I'm going for before I buy them.

I got the following parts:

Aero Precision M5 Builder Set w/ ATLAS S-ONE Handguard

JP Rifles 22" Super Match Barrel

Seekins Precision SELECT ADJUSTABLE GAS BLOCK

So how can I reasonably figure out how far down the barrel where the gas block will sit, and how far down the hand-guard will cover?

You say "I got the following parts" as if you've already bought them, but in your second post you state you edited the first post to show a different gas block, so I'll ask the following question- have you already bought parts, and if so, what are they specifically? Any components you've already bought will dictate to some degree the other parts options to complete the build.

 

[thirstman]

You say "I got the following parts" as if you've already bought them, but in your second post you state you edited the first post to show a different gas block, so I'll ask the following question- have you already bought parts, and if so, what are they specifically? Any components you've already bought will dictate to some degree the other parts options to complete the build.

I am grammatically incorrect yes. I meant to say I have merely selected them. I have only bought the Aero builder kit

 

[thirstman]

I am trying to find a clamp on adjustable tool-free gas block with .875 diameter

 

[Snuby642]

That handgaurd you selected won't be long enough.

 

[thirstman]

That handgaurd you selected won't be long enough.

I did want unfettered access to the gas block so I don't have to work around it or take it off to make adjustments. are you sure it will not work?

 

[n2ishun]

The barrel says it's rifle +2.
You didn't say how long of a handguard you have chosen.
The Seekins gas block has a throw lever that will not work under a handguard because there is not enough room to...uhh...throw.

Exactly which question did you want answered ?

 

[Snuby642]

The +2 on rifle lenght gas will have the gas block hanging out the front of the handgaurd if that's what you intend.

Most people would cover that as they get hot as hell.

The gas block adjustments are not that hard to reach. I have had to take a file to a handgaurd to open up access a tiney bit to get tool strait in on the screw.

 

[Milf Dots]

I am grammatically incorrect yes. I meant to say I have merely selected them. I have only bought the Aero builder kit

You said you already bought the Aero build kit- which handguard length did you choose with it- 12" or 15"?

Rifle length gas tube on AR10 and AR308/308 AR can differ- they're not standardized length like ar15, so you should really call JP and ask them for the max handguard length that'll keep the gas block's tool-less adjustment lever uncovered and accessible.

 

[msgriff]

For a 15" Atlas S-One with a rifle length gas system. the shoulder of the gas journal is 2-5/16" from the front of the handguard. For a +2 gas system, the back of the AGB should tuck 5/16" inside the handguard. That AGB is also set screw, not clamp on. I would also verify that the 0.875 AGB will fit, even though it's just the back of the AGB under the rail.

 

[r.tenorio671]

...here ya go, the 15" HG will cover just about any gas block you choose on a standard "rifle length gas system"

... if you want an adjustable, you might want to check out the SLR offerings, they do have one to fit the .875 journal >>> https://slrrifleworks.com/gas-blocks/melonite-qpq-finish/adjustable/sentry-8-series/

...the SLR's adjust from the front. If the HG is a true 15", the front of the SLR gas block will be approximately 1" inside the front edge of the HG, easily reachable with a standard "L" shaped hex key (the SLR's adjustment screw takes a 2mm). Of more concern is the inside diameter (ID) of whatever handguard you choose, you don't want the ID too small and end up with the gas block making contact with the handguards inner walls. a "set screw" type gas block is smaller OD than the "clamp" type.

 

[r.tenorio671]

...here ya go, the 15" HG will cover just about any gas block you choose on a standard "rifle length gas system"

... if you want an adjustable, you might want to check out the SLR offerings, they do have one to fit the .875 journal >>> https://slrrifleworks.com/gas-blocks/melonite-qpq-finish/adjustable/sentry-8-series/

...the SLR's adjust from the front. If the HG is a true 15", the front of the SLR gas block will be approximately 1" inside the front edge of the HG, easily reachable with a standard "L" shaped hex key (the SLR's adjustment screw takes a 2mm). Of more concern is the inside diameter (ID) of whatever handguard you choose, you don't want the ID too small and end up with the gas block making contact with the handguards inner walls. a "set screw" type gas block is smaller OD than the "clamp" type.

View attachment 7777671

...FWIW, this is a 13.7" HG on a 18" barrel with a standard "rifle length gas system (RLGS)" with an SLR set screw type gas block...although it's a AR15, what is important for you is the length of the handguard in relation to the gas block on a RLGS...there is no difference in an AR15 -vs- AR10 when it comes to the gas system lengths.. good luck!

 

[Milf Dots]

...FWIW, this is a 13.7" HG on a 18" barrel with a standard "rifle length gas system (RLGS)" with an SLR set screw type gas block...although it's a AR15, what is important for you is the length of the handguard in relation to the gas block on a RLGS...there is no difference in an AR15 -vs- AR10 when it comes to the gas system lengths.. good luck!

The bolded statement above is factually incorrect. The AR10/AR 308/308 AR isn't a standardized platform to the same degree as the AR15.

Rifle Length Gas Tube Differences​

Rifle Length AR-10 308 and AR-15 Gas Tubes​

The rifle-length gas system is another crucial difference between the Armalite AR-10 and the AR-15 and 308 AR/AR 308. Armalite uses a gas tube that is approximately .325″ longer than an AR-15’s or nearly all 308’s. In addition to Armalite, Futon Armory also uses the AR-10 rifle length gas tube.

AR-10 308 AR Compatibility Reference Guide | AR 308 vs AR 10

Compatibility Reference Guide - Understand and research the parts interchangeability and differences between the AR-10, AR-15, 308 AR and AR 308 rifles

308ar.com

"Armalite developed the AR-10 first. They later developed the AR15 model. Both original rifles were rifle length gas systems. the AR-10 Rifle length gas tube was 15.5". When Armalite developed the AR15, the Rifle length gas tube was 15.25"... I am not the designer, nor the engineer on these platforms. I'm just delivering information. Eugene Stoner was the designer, and he developed these two platforms in similarity, but independent of each other. They share alot, but the differences cannot be overlooked. Eugene Stoner had HIS REASONS for changing that gas system to a shorter length tube, when he went on to develope the AR15/M16, from his ORIGINAL design of the AR-10... He's WAY smarter than me on that stuff, but that can't be ignored. Many manufacturers these days are ignoring that, completely..."

Gas tubes, barrel gas ports, and buffer weight

This might end up as a long thread, but it shouldn't be too long. It's a lecture, or a sermon, depending on how you look at it, and I'm not looking for feedback on what I'm about to say. I'm publishing information. In reality, it's pretty damned simple, but manufacturers are making it difficult f...

forum.308ar.com

 

[r.tenorio671]

The bolded statement above is factually incorrect. The AR10/AR 308/308 AR isn't a standardized platform to the same degree as the AR15.

Rifle Length Gas Tube Differences​

Rifle Length AR-10 308 and AR-15 Gas Tubes​

The rifle-length gas system is another crucial difference between the Armalite AR-10 and the AR-15 and 308 AR/AR 308. Armalite uses a gas tube that is approximately .325″ longer than an AR-15’s or nearly all 308’s. In addition to Armalite, Futon Armory also uses the AR-10 rifle length gas tube.

AR-10 308 AR Compatibility Reference Guide | AR 308 vs AR 10

Compatibility Reference Guide - Understand and research the parts interchangeability and differences between the AR-10, AR-15, 308 AR and AR 308 rifles

308ar.com

....yes, you are correct and I should have been more specific. As the OP is using an Aero M5 receiver set, it is what Aero claims is a "DPMS" pattern, which DPMS patterns "generally" follows the gas system dimensions associated with the AR15, hence my reply/statement. But as you pointed out, there still isn't a "standard" when it comes to the larger format AR platforms. The barrel the OP posted a link to indicates it's an "Extra long (+2 from rifle length)", it would be advisable he query JP directly to get the specific dimensions.

 

[Milf Dots]

....yes, you are correct and I should have been more specific. As the OP is using an Aero M5 receiver set, it is what Aero claims is a "DPMS" pattern, which DPMS patterns "generally" follows the gas system dimensions associated with the AR15, hence my reply/statement. But as you pointed out, there still isn't a "standard" when it comes to the larger format AR platforms. The barrel the OP posted a link to indicates it's an "Extra long (+2 from rifle length)", it would be advisable he query JP directly to get the specific dimensions.

It'd be great if the industry could settle on an AR10/308AR set of standards like we have for the AR15, but I'm not sure that'll ever happen!

 

[r.tenorio671]

It'd be great if the industry could settle on an AR10/308AR set of standards like we have for the AR15, but I'm not sure that'll ever happen!

...true, but companies desire to rise above their competitors by having a "uniqueness" that differentiates them which most times leads to a "proprietary" aspect, not an "enhancement or improvement" on the existing standard(s), unfortunately...