Adjustable gas block

[AntiHippie]

...for an 8" .300BLK pistol build. I have a lo-pro Aero-Precision one on there now. Still haven't fired the thing yet, and may work just fine as it is, but a local (reputable, very knowledgeable) gunsmith was extolling the virtues of an adjustable gas block the other day when he took a look at the gun. Something to do with the massive gas port in the AP barrel, short gas system, etc.

Any thoughts on the best bang-for-the-buck adjustable?

May not bother, but I want to look at contingencies now. Planning contingencies is kind of what I do.

 

[Golddiggie]

For 300 Blackout you use either pistol or carbine length gas tubes on all barrels. My 10.5" 300 Blackout barrel functions just fine with the carbine length gas tube and standard (low profile) block. I know another NES member with an 8.1" 300 Blackout barrel that has the pistol buffer tube and standard (low profile) block that has zero issues.

I suspect the person/gunsmith you saw doesn't know jack about 300 Blackout systems.

BTW, they run 300 Blackout pistols/SBR's/rifles with standard gas blocks all day long.

 

[warwickben]

Adjustable gas block isn't a bad idea . Some people dial back the pressure till the action moves just enough to cycle.
Another good reason to have one is if you have a can .

They also make self regulating gas blocks . You basically set to how you like it and if you use hotter rounds etc it will just bleed off the extra pressure.

 

[ColdDayInHell]

Adjustable gas block isn't a bad idea . Some people dial back the pressure till the action moves just enough to cycle.
Another good reason to have one is if you have a can .

They also make self regulating gas blocks . You basically set to how you like it and if you use hotter rounds etc it will just bleed off the extra pressure.

+1

Ben the Builder...

 

[warwickben]

+1

Ben the Builder...

Lol ...
Also there commonly used on piston setups.
My setup bleeds off extra pressure on its own .

 

[ColdDayInHell]

Still want my AMD soon. No rush. Have a present for you waiting Ben. And it's not flesh

 

[AntiHippie]

For 300 Blackout you use either pistol or carbine length gas tubes on all barrels. My 10.5" 300 Blackout barrel functions just fine with the carbine length gas tube and standard (low profile) block. I know another NES member with an 8.1" 300 Blackout barrel that has the pistol buffer tube and standard (low profile) block that has zero issues.

I suspect the person/gunsmith you saw doesn't know jack about 300 Blackout systems.

BTW, they run 300 Blackout pistols/SBR's/rifles with standard gas blocks all day long.

It's a pistol length gas system. His point was that it will likely be too 'wide open'. Way more gas than necessary. I know for sure he knows quite a bit about .300 Whisper 'stuff', and he is highly reputable. No reason to doubt him. He does, after all, have logic on his side. I just don't have ANY experience with .300BLK beyond building this one pistol that's still not 100% complete, so I don't know that it will make enough of a difference in how nice it shoots to justify the cost. Unless, of course, the cost isn't that much.

At this point it's really just a what-if kind of thing, a contingency, but I like to plan these things out. I'll know better when I get a chance to shoot this gun, and take this gunsmith up on his offer to shoot one of his with a dialed in adjustable block for comparison.


Have you toyed with adjustables at all, or are they just not needed? You seem to be one of the NES 'go-to' guys for blackout stuff, so I'd appreciate your thoughts on it.

 

[atilla]

Still want my AMD soon. No rush. Have a present for you waiting Ben. And it's not flesh

spoiler alert: it's a skin flute.

 

[dcmdon]

For 300 Blackout you use either pistol or carbine length gas tubes on all barrels. My 10.5" 300 Blackout barrel functions just fine with the carbine length gas tube and standard (low profile) block. I know another NES member with an 8.1" 300 Blackout barrel that has the pistol buffer tube and standard (low profile) block that has zero issues.

I suspect the person/gunsmith you saw doesn't know jack about 300 Blackout systems.

BTW, they run 300 Blackout pistols/SBR's/rifles with standard gas blocks all day long.

You aren't making any sense. If it functions "just fine" it could still be grossly overgassed.

An adjustable gas block is always a good idea. To the OP. I like the JP aluminum block. Its a bit ugly, but its light and has a rail that you can mount a front sight on if you like. I've used 3 of them in the last year and they all went on great.

An adjustable gas block can enhance almost any gun. It doesn't matter if its .223, .300 blk, or 500 Beowulf, most barrels are set up to provide more gas than is necessary because people don't complain that the gun recoils too much. But they do complain if the gun doesn't cycle properly.

And to all the theoreticians out there. Don't bother to comment if you haven't every tried one. The transformation can be significant.
Don

 

[AntiHippie]

You aren't making any sense. If it functions "just fine" it could still be grossly overgassed.

An adjustable gas block is always a good idea. To the OP. I like the JP aluminum block. Its a bit ugly, but its light and has a rail that you can mount a front sight on if you like. I've used 3 of them in the last year and they all went on great.

An adjustable gas block can enhance almost any gun. It doesn't matter if its .223, .300 blk, or 500 Beowulf, most barrels are set up to provide more gas than is necessary because people don't complain that the gun recoils too much. But they do complain if the gun doesn't cycle properly.

And to all the theoreticians out there. Don't bother to comment if you haven't every tried one. The transformation can be significant.
Don

That's along the lines of what the smith was saying. I suppose I should have been more clear in my original post.

Still haven't fired the thing. Might be just fine as it is, but it doesn't hurt to start pricing out now in case I do decide it's worth trying.

 

[dcmdon]

Let me just add one caveat to what I said above.

If you have a gun that going into combat with, (not something plan to do. I'm an IT PM and a dad first and foremost) having it be overgassed is not a bad thing. When the gun gets filthy and dry and in particular the chamber is dirty, having all that gas available to shove a heavy buffer/boltcarrier back against a heavy spring which then sends the bolt into battery with a lot of authority, is a very very good thing. It helps to ensure that the gun will continue to run even if dirty.

But if the gun will be kept clean and well cared for, then turning down the gas and lightening the reciprocating mass is no problem. I've done carbine courses with adjustable guns that were tuned to run on the minimum and I had not problems with them. I did stick a chamber brush into it and squirt some oil into the bolt carrier at the beginning of each day and at lunch and the gun has run reliably. But even still, this gun has never run dirty. So I couldn't attest to how it would do if it was dirty. By all logic, it should not do as well as a standard gun.

But remember what dirty really is. Even a home defense or police gun would be fine with an adjustable gas system. In that case, I'd probably give it a bit more than is necessary just to have a larger margin of error. But these guns are typically stored somewhere clean and safe and then used. So dirt should not be a problem.

Don

 

[2nd-amendment]

I have used both Syrac and SLR adjustable blocks and would use either of them again. They both have features that keep the adjusting screw from adjusting on its own, which can happen with some other designs. SLR's design allows for easier cleaning of the block, but I haven't seen the need to clean mine.

Both of them run about $100.

 

[dcmdon]

Do either of them allow adjustment from the end?

every gun I've built with one has used a handguard that stopped at the gas block. I'd like to find an adjustable gas block I can run the handguard over and adjust from the end.

 

[warwickben]

Do either of them allow adjustment from the end?

every gun I've built with one has used a handguard that stopped at the gas block. I'd like to find an adjustable gas block I can run the handguard over and adjust from the end.

You can easily make a adjustable gas block .
The truck is doing it with needing a Allen wrench .
Drill a hole straight through where the gas tube goes in. Tap the hole up to the port hole for the barrel . Then just use two set screws the first one controls the flow and the second one locks the first one from moving.

I did this with my psl carbine . Since there's no official gas port hole size for Ak's shooting 54r with ak gas length . I'm debating doing this with my full size psl so I can shoot heavy bullets with out the carrier smashing into the rear if the receiver.
Most guys just tap the port hole and use set screws with different size holes drilled in the center . I did it in the out side so I don't need to field strip the rifle to dial it in .

I'm in nh on vacation but I can post a pic when I get back .




Edit, I was half awake with a ar you need to fill a hole below the port for the gas tube since the tube goes last the hole for the barrel.

 

[AntiHippie]

Interim update:

Tried another Blackout pistol similar to the one I'm building with an adjustable block. Difference between wide open and open just enough to cycle the weapon was very noticeable. My inexperienced, non-credible, and largely unscientific opinion is - yes, these guns are grossly over gassed in standard form.

Ended up ordering the Syrac Ordnance Gen II. Got on a roll ordering the other final parts for the build and added it to the shopping cart, placed the order before I could second guess myself. Rationalizing it by reminding myself I DID save quite a bit on the other parts with the Labor Day sale at Primary Arms (math still doesn't work out in my favor, but that rationale is what my wife uses when she goes shopping, so it's worth a try). Really need to put a hard stop on spending money on gun parts after this so I can save money for more guns.

 

[AntiHippie]

Test fired today. Only down side is after I fired a dozen or so rounds, the 'click' wasn't noticeable when I adjusted it. Noticeable gumminess in the setscrew.

This little gun is FUN to shoot, though! Needs a cleaner trigger, optic, and it's own BCG and charging handle. I had forgotten I robbed the BCG out of my other AR until I threw a full magazine in it and hit the bolt release - and there was no bolt to release.



Appreciate everyone's input. The adjustable was an unanticipated expense, but I'm glad I did it. Wasn't a knock your socks off difference, but most definitely noticeable.

 

[dcmdon]

Aimsurplus is running a special on Geissele triggers for $109. I bought 3.

 

[AntiHippie]

Obligatory photo.

 

[dcmdon]

Very nice.