AGB on 7.5" AR pistola?

Slacker

Slacker

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Anyone have input on the usefulness (or lack thereof) of an AGB on a 7.5" AR? Obviously pistol length gas, probably overgassed.
I don't think barrel makers use different sized gas ports for pistol/carbine/midlength barrels.
(Or do they?)

I'd like to be able to shoot low (er) pressure heavy bullets in this pistol.
77gr with a faster powder in a 7.5" barrel makes sense.
(Yes, I know 300blk is already invented) ;)
 
I put a superlative arms adjustable gb on my latest build and like it so far. It’s supposed to vent extra gas out the front maybe it would work for you.


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Slacker said:
Anyone have input on the usefulness (or lack thereof) of an AGB on a 7.5" AR? Obviously pistol length gas, probably overgassed.
I don't think barrel makers use different sized gas ports for pistol/carbine/midlength barrels.
(Or do they?)

I'd like to be able to shoot low (er) pressure heavy bullets in this pistol.
77gr with a faster powder in a 7.5" barrel makes sense.
(Yes, I know 300blk is already invented) ;)
Click to expand...

The gas ports definitely vary in size based on the barrel and gas length. They have to bleed off more pressure more quickly the shorter the barrel. That’s why a barrel that gets cut back may function differently than a factory barrel of the same length. If you have a Carbine length 16” barrel you cut back to 10.5” and a factory 10.5” Carbine gas, I’d put money on the factory barrel having the larger gas port.

Rainier Arms rebrands superlative gas blocks; I’d recommend either one that is in stock or cheaper...I have two of them
 
The two Aero 7.5"'s I have used were both slightly overgassed. They used an H2 buffer and that straightened them out about perfect. Edit: with 55 grain federal.

So might be fine without adjust gas.
 
Last edited:
Slacker said:
Anyone have input on the usefulness (or lack thereof) of an AGB on a 7.5" AR? Obviously pistol length gas, probably overgassed.
I don't think barrel makers use different sized gas ports for pistol/carbine/midlength barrels.
(Or do they?)

I'd like to be able to shoot low (er) pressure heavy bullets in this pistol.
77gr with a faster powder in a 7.5" barrel makes sense.
(Yes, I know 300blk is already invented) ;)
Click to expand...

My .02

Put an AGB on everything. Escpecially if you’re reloading for it.

The little extra now saves down the road
 
honestly on a 5.56 pistol, I would just changed the buffer to an H or H2 and call it a day. The one exception is if you're running a suppressor.

Overgassed ARs are really a blessing for reliability. That's why nearly everything PSA sells is overgassed, including my PA10 .308 AR. I considered putting an AGB on it but just coverted to
a rifle buffer setup over the carbine buffer.
 
NKD said:
The two Aero 7.5"'s I have used were both slightly overgassed. They used an H2 buffer and that straightened them out about perfect. Edit: with 55 grain federal.

So might be fine without adjust gas.
Click to expand...

They are still overgassed, the H2 just masks the symptoms :p


I like the Superlative Arms / Rainier adjustable gas blocks. The don’t restrict the gas (which sends the crap down the barrel). They bleed off the excess pressure from the gas block itself which reduces the blowback and ejection port noise.

concepthomes1 said:
I need one for my suppressor but man! Those SLR Rifleworks blocks are pricey....
Click to expand...

My recommendation

https://suparms.com/collections/adj...table-low-pro-solid-gas-block-melonite-finish

They make them for .625”, .750”, .875” in clamp on and set screw
 
11B CIB said:
Must of missed that! My bad. I am ashamed
Click to expand...

No, you didn’t miss anything. I just know Slacker well, and know he doesn’t want to spent 80-120$ on an adjustable gas block! Lolz.

I’d had guns with fixed blocks, but since going to an adjustable, I have replaced the other fixed ones. To me, gas is so important for smooth cycling. Proper gas just shoots and cycles so much better.
My newest project is a irons carbine with a front sight post. It is also adjustable. To me it’s worth it and I can’t find any reason not to have it.

All that said, if it were a truck gun or shtf gun I wouldn’t hesitate to use one that was overgassed and tame it with a heavier buffer. I think the extra gas and mass likely is most reliable, at least until it starts to wear stuff.
 
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