Proper Gas 12" 6.5 Grendel

[MtnCreek]

I want to try to get this right first time.

What I have:
PSA carbine buffer tube/spring/buffer (wanting to keep the tube, possibly replace buffer & spring).
Faxon 12" Grendel, carbine gas.

I want it to reliably function suppressed and unsuppressed. I intend to reload the brass. A left hand shooter will use it a good bit (I assume that disqualifies adjustable BCG's, but don't know that for fact).

I figured someone here may have worked the kinks out of a similar setup and have some advice. Thanks.

 

[MtnCreek]

One last try for info on a proven combo of gas block, BCG and buffer. Thanks.

 

[Strykervet]

I have one with a Lilja 11" but I haven't shot it yet. I do have a winning formula for most all my AR builds and that includes the JP full mass BCG (it's slick as goose shit dry) and whatever buffer is listed on that buffer chart on barfcom. It's an H2 I think but not positive. That chart has always come through for me too. Gas block on this one I think is a Geissele set screw/pin on but it's possible I used a quality set screw block because it has a URX4 on it. I don't bother with adj. gas blocks, never have after hassling with one, and all my rifles and SBR's work fine suppressed or not, subs or supers in the .300BLK's.

Grendel does have more recoil so I'm sure the buffer won't be a standard one.

There are some guys on here with Grendel SBR's and some swear by the adj. gas blocks, so different strokes I guess. Maybe they're just not around or not seeing it. I just saw it myself. They may chime in eventually.

 

[Srikaleak]

Mine is still more concept than proven but I plan on running adjustable gas block with full weight bcg as well. Parts supplied by JP. You'll probably have your rifle built before mine but I'll update when the build is complete (waiting on tax stamp and funds)

 

[Yondering]

One last try for info on a proven combo of gas block, BCG and buffer. Thanks.

Not sure what exactly you're asking for here, brand recommendations? Everything depends on your gas port size, the rest of the operating system reacts to that. .073-.075-ish should be about right, but that depends on your loads too. That port size with all standard other parts will be perfect for loads with 8208 but a bit overgassed for CFE223. If your port size is larger than that (I have heard Faxon barrels are ported larger but don't know first hand), you'll need an adjustable gas block, probably a good idea to have one anyway regardless. The brand doesn't matter much unless you want click adjustments; I use Seekins blocks.

Regardless what setup you end up with, if it runs unsuppressed it will be overgassed with the suppressor unless you make a change between suppressed and unsuppressed. My choice was to use a Bootleg adjustable bolt carrier; position 1 for 8208 loads unsuppressed, position 2 for CFE223 loads, and position 4 suppressed. That's with a carbine buffer and spring, although you could use an H1 buffer with no real difference.

I prefer to use the Bootleg carrier for adjustment instead of a click adjustable gas block because there is visual confirmation of what setting it's on. It is a more expensive setup though.

 

[flyer]

JSE has some POF Dictator gas systems, I think the POF guys use them for going from bare muzzle to suppressed.

On the other hand, I think a lot of people are having success with Faxon 11.5" .223 barrels with mid-length gas which reduces the port pressure and the dwell (especially when suppressed).

You might have the wrong barrel for that job.

Also, I think adjustable carriers are not as good as adjustable gas blocks because the adjustable carrier doesn't limit the amount of gas that gets blown in to your upper after the gas key uncovers the gas tube, you'll probably get more gas in your face with an adjustable gas key.

 

[Yondering]

You might have the wrong barrel for that job.

Also, I think adjustable carriers are not as good as adjustable gas blocks because the adjustable carrier doesn't limit the amount of gas that gets blown in to your upper after the gas key uncovers the gas tube, you'll probably get more gas in your face with an adjustable gas key.

No to both of those.

The Grendel works great in short barrels, suppressed or not. He just has to deal with the additional gas when suppressed.

As to the adjustable bolt carriers - don't knock em until you try them. You do not get more gas in your face; just the opposite and that is the whole point. Please don't spread false information.

Most of the gas that gets into the receiver comes down the bore; a little extra gas from the tube is insignificant. The biggest reduction in gas to the receiver is from delaying bolt opening, and that's what the adjustable bolt carrier does.

It's true that an adjustable bolt carrier isn't a substitute for restricting gas at the gas block on an overgassed rifle, but as a method to switch between suppressed and unsuppressed they are excellent.

 

[flyer]

I didn't say anything about short barrels not working just mid-length gas might be better for running suppressed in a 12" barrel.

You have a decent point about gas coming back through the barrel but delaying bolt unlock is done pretty much the same way with an adjustable gas block or gas key and I maintain that a wide open gas block and gas tube are going to dump more gas back than going through the restriction of an adjustable gas block.

And now back to mid-length gas systems, it delays bolt opening by reducing the port pressure and dwell and combined with an adjustable gas block you can tune it for the maximum bolt opening delay which is what will minimize gas in your face.

Getting a little more aggressive, if you minimize your buffer and possibly carrier weight, you could increase your carrier speed a bit and shut off that open barrel with a newly chambered round ASAP. That might even help when running with a bare muzzle, mid-length gas and less dwell than suppressed.

 

[Yondering]

You know, instead of just guessing and making up theories of what might work, you could just leave it to the people who've already done short barreled Grendels suppressed. Some of us don't have to guess...

We don't use mid length gas systems on 12" Grendel barrels. A carbine gas port is what you want.