Bootleg Adjustable BCG

[WoodieSC]

Anyone shooting an AR-15 with a suppressor along with an adjustable BCG? What’s your take on it vs an adjustable gas block and/or a blow-back reducing charging handle? My take is there’s less chance of carbon pluggage, etc, but don’t have any experience with one yet.

[Tha Dick]

Haven't dealt with the adjustable BCG. I was dealing with over gassing on my 11.5" suppressed SBR last month. You'll find that tuning to right at last round lock back will make it a lot quieter.

The problem will be cutting down the gas enough. I always thought it was the "sonic Crack" of the 5.56 that was still so loud even with the can, buts it's the bolt opening to fast and you're getting the noise from the chamber. I have a H3 buffer and heavy buffer spring and was still over gassing. So I tried an Anderson Mfg. and also a Odin Werks adj gas block, both turned all the way closed would still not cut the gas down enough. After researching it , it appears that manufactures have different gas port sizes in the barrels. My 11.5" barrel must have a larger gas port, I didn't take the time to measure it.

I finally talked to Barnes Precision and he makes an adjustable gas tube that will cut the gas all the way off, it worked. I was able to adjust my gas to last round lock back and it's "A Lot" quieter than when it was over gassing and ringing my ears.

Simply drill a hole in the handguard and you're ready to go.

https://usamade-ar15parts.com/produc...le-gas-system/

[Tha Dick]

PS, mine was carbine length gas. If yours is rifle length and 16" barrel you might be good with a H3 buffer and adj gas block. All depends on the ammo, length gas system, length barrel and the gas port size. You won't know till you start playing with it.

[Palmetto Bug]

Tuning is all about adjusting where along the pressure curve the reload happens. The adjustable gas block and/or adjustable BCG reduce only a tiny bit of gas coming through the gas tube but that is mostly to delay when the bolt gets unlocked. It's more about fine tuning the timing the bolt opening than directly reducing the volume of gas. If the unlock is delayed, more gas heads down the barrel than back through the receiver. An adjustable gas block or BCG do the same thing, it's just a matter of where you throttle the small amount of gas. Depending on your handguard, it might be easier to turn a screw on the BCG than on the front of the gas block. I need a weird, very long hex wrench to adjust one of my gas blocks. My guess would be that the adjustable BCG would be more likely to cause crud buildup in the tube than throttling the gas from ever entering the tube with an adjustable gas block. Truth is, though, once I get a gun tuned so it will cycle sub and super sonics without hitting the back of the receiver too hard, with and without the suppressor, I rarely have to adjust them again.

The buffer weight controls how quick the initial jump of the bolt is, which further times when the chamber is vented. It seems to have more effect than adjusting the tube gas. Gas tube length (pistol, carbine, intermediate, rifle) most drastically determines where in the pressure curve the reload cycle happens.

Blow back reducing charging handles simply try to seal the exit of the gas from out the back of the receiver into your face.

[USMCsilver]

What caliber? What barrel length?

Sent via Galaxy s23 Ultra using Tapatalk

[WoodieSC]

What caliber? What barrel length?

The applications would include 5.56 w/16" & medium gas tube and a 20" & a rifle length gas tube.

PS, mine was carbine length gas. If yours is rifle length and 16" barrel you might be good with a H3 buffer and adj gas block. All depends on the ammo, length gas system, length barrel and the gas port size. You won't know till you start playing with it.

Tuning is all about adjusting where along the pressure curve the reload happens. The adjustable gas block and/or adjustable BCG reduce only a tiny bit of gas coming through the gas tube but that is mostly to delay when the bolt gets unlocked. It's more about fine tuning the timing the bolt opening than directly reducing the volume of gas. If the unlock is delayed, more gas heads down the barrel than back through the receiver. An adjustable gas block or BCG do the same thing, it's just a matter of where you throttle the small amount of gas. Depending on your handguard, it might be easier to turn a screw on the BCG than on the front of the gas block. I need a weird, very long hex wrench to adjust one of my gas blocks. My guess would be that the adjustable BCG would be more likely to cause crud buildup in the tube than throttling the gas from ever entering the tube with an adjustable gas block. Truth is, though, once I get a gun tuned so it will cycle sub and super sonics without hitting the back of the receiver too hard, with and without the suppressor, I rarely have to adjust them again.

The buffer weight controls how quick the initial jump of the bolt is, which further times when the chamber is vented. It seems to have more effect than adjusting the tube gas. Gas tube length (pistol, carbine, intermediate, rifle) most drastically determines where in the pressure curve the reload cycle happens.

Blow back reducing charging handles simply try to seal the exit of the gas from out the back of the receiver into your face.

TD and PB, I appreciate your commentary about the various means to fine tune a rifle. I've read about them all but haven't thus far gone any farther than the gas block adjustment(s) and wasn't thinking about the additional fine tuning aspect.

When I first posted the question I was thinking about a 20" rifle, .223 Wilde chamber (fwiw), with a rifle length gas tube that I already have 'fairly' well tuned using a Seekins adjustable gas block, full-auto NiB BCG, standard AR-15 spring, and an H2 buffer. I have not yet really tested it on numerous loads. This block can be adjusted without removing the hand guard, but I was thinking ahead as to possible adjustment(s) needing to be made when shooting with vs without a suppressor.

I ought to clarify up front that my thoughts are/were(?) that since I only shoot one rifle at a time, there's no sense in setting up every rifle with every bell and whistle part in order to shoot it with or without a suppressor as it quickly adds up if just a few parts can be easily swapped around. A suppressor, at least for awhile, would be swapped to whatever rifle I was going to use, and each rifle would be tuned via adjustable gas blocks, Sprinco springs (white/red, blue, red?) and/or heavier buffers. If the best plan is to also equip each rifle with an adjustable gas tube, one starts to need a cheat sheet etched in the hand guards as to which rifle needs which adjustment... Thus, the thought was in place of the adjustable gas tubes is to swap the adjustable BCG along with the suppressor, and since there are four adjustment setting on the BCG it seems like a pretty easy thing to do. Supposedly this also helps cut down on gas blow-back in the face.

Or would it be better to fine tune the rifle(s) WITH a suppressor, and then make the adjustment(s) or buffer weight change(s) as needed to shoot finely tuned WITHOUT a suppressor, and use a blow-back reducing charging handle instead of the adjustable BCG?

I had forgotten about the adjustable gas tubes and agree that may be a better option than the adjustable BCG on any particular rifle so as to minimize carbon build-up in the tube. However, this carbon build-up is also why it seems like other than an initial adjustment with an adjustable gas block, which will (I assume) inevitably get carbon build-up locking the adjustment screw in place, an AGB shouldn't be counted on long term for making adjustments. Isn't the adjustable gas TUBE area also prone to carbon buildup? The gas tube basically blows itself clean when fired, so it would seem that cleaning the BCG is a lot easier option, again, assuming it also provides the benefit of reducing blow-back in the face.

My head hurts so I'll stop and proofread this tomorrow. If you see it in the meantime and my comments and questions make any sense, please reply.

Thanks.