Is an adjustable gas block even needed?

[depletedyourcranium]

Zero hassle, drop-in option that you adjust through the ejection port, vs carbon-welded AGB up under the handguard accessible only with tiny Allen wrenches.

I think these are the ticket for anyone looking for some more precise adjustment. A big bonus is that you swap it from rifle to rifle unlike a gas block (practically, anyway).

[GhostRider32]

Considering what we spend on our rifles, the AGB is very cheap. I just bought a Seekins for a little over $50. I like tuning my gun to run at the minimum gas necessary.

[Bowfisher]

Just picked up an used upper, it's a nice build, but wishing it had an AGB for when my cans get here..

What's the best/easiest to adjust brands?

[A5BLASTER]

Just picked up an used upper, it's a nice build, but wishing it had an AGB for when my cans get here..

What's the best/easiest to adjust brands?

I have been wojeck lately, they work good and don't break the bank.

[Bowfisher]

I have been wojeck lately, they work good and don't break the bank.

Thank you sir.

[SDW]

None of my Grendels have adjustable gas blocks, but I do have an adjustable gas bolt carrier in my 12" pistol, and will be buying Bootleg adjustable gas carriers as my go-to carrier from now on I think.

I had to do a search as soon as I read it. Interesting approach. And it's not even all that expensive at the moment. I think their site says about $180? I watched a couple of videos so far. I'm still unsure how it actually controls the gas. Does it just restrict flow into the... "piston" internal area of the carrier? I don't understand what happens with the unwanted/excess gas yet, but for now I'll assume simply that "it works".

As far as needing an adjustable gas block, I didn't think I'd need one. My Grendel is pure Rifle. A1 (rifle) type buffer system, 20" barrel and rifle gas length. Barrel is Ballistic Advantage. Gas port's around 0.093-ish. I assume that my system produces "just enough" gas to cycle the bolt properly when I use Hdy Black 123gr ammo. All my brass lands in a night little area a couple of feet away, at about 3:30. This is when shooting prone form a bipod. This was after I swapped my recoil spring from a Tubbs flat-wire to a standard rifle spring. FYI, in another rifle the Tubbs spring works great with 5.56. But my Grendel ammo didn't like it, wouldn't cycle fully, so I switched back to a standard spring.

However, this rifle will not cycle the 90gr American Eagle varmint ammo I decided to try. I had to fire these ones like a single-shot---One round in the magazine at a time. They ejected fine but the bolt would not lock back fully. I assumed that the lighter bullets don't provide enough oomph for the recoil system. But could I be wrong here? Could it be providing too much, too fast? The MV was around 2900 as I recall. I still plan to try the 90gr AE ammo in this upper, using one of my carbine lowers to see if that makes a difference. Otherwise, this adjustable carrier might be the way to go.

[Sixoeight]

I had to do a search as soon as I read it. Interesting approach. And it's not even all that expensive at the moment. I think their site says about $180? I watched a couple of videos so far. I'm still unsure how it actually controls the gas. Does it just restrict flow into the... "piston" internal area of the carrier? I don't understand what happens with the unwanted/excess gas yet, but for now I'll assume simply that "it works".

As far as needing an adjustable gas block, I didn't think I'd need one. My Grendel is pure Rifle. A1 (rifle) type buffer system, 20" barrel and rifle gas length. Barrel is Ballistic Advantage. Gas port's around 0.093-ish. I assume that my system produces "just enough" gas to cycle the bolt properly when I use Hdy Black 123gr ammo. All my brass lands in a night little area a couple of feet away, at about 3:30. This is when shooting prone form a bipod. This was after I swapped my recoil spring from a Tubbs flat-wire to a standard rifle spring. FYI, in another rifle the Tubbs spring works great with 5.56. But my Grendel ammo didn't like it, wouldn't cycle fully, so I switched back to a standard spring.

However, this rifle will not cycle the 90gr American Eagle varmint ammo I decided to try. I had to fire these ones like a single-shot---One round in the magazine at a time. They ejected fine but the bolt would not lock back fully. I assumed that the lighter bullets don't provide enough oomph for the recoil system. But could I be wrong here? Could it be providing too much, too fast? The MV was around 2900 as I recall. I still plan to try the 90gr AE ammo in this upper, using one of my carbine lowers to see if that makes a difference. Otherwise, this adjustable carrier might be the way to go.

I believe the bootleg actually vents excess gas off out the ejection port. There are two ways to control gas in an AR, restrict it's flow or leak it off to the atmosphere. Some AGB also vent gas out the front this just does it at the bolt.

I have not tried the bootleg but I have used the nicer version of the Odinworks AGB with the detent adjustment. It worked great and with my handguard setup was hidden but accessable from the front. I loved the setup except one big problem, it was on an AR10. Too heavy.

[LRRPF52]

Bootleg ABC acts like any other BCG, just with a restriction shaft with different openings to control gas flow into the Stoner Internal Expansion System of the AR15.

Excess gas is vented like any other Stoner BCG. Yes, I order them and immediately pull the 5.56 bolts out, to add to my parts box with countless other 5.56 bolts I doubt I'll ever use. (I have a lot of 5.56 rifles too.)

[SDW]

Bootleg ABC acts like any other BCG, just with a restriction shaft with different openings to control gas flow into the Stoner Internal Expansion System of the AR15.

Excess gas is vented like any other Stoner BCG.

Thanks. So it simply restricts flow (as opposed to "dumping" it somewhere, somehow), like most adjustable GBs on the market. Interesting idea. It has four settings, one being specific supposedly to suppressor usage. Might be marked with an "S"? Is this setting the most turned down/restrictive of the range? Some of the opinions I've read state that with just four settings, as opposed to an "infinite" range of adjustment like an AGB, it's not the best device for tuning your recoil system to various ammo. It's said this the ideal application is confined to a rifle that wears a suppressor on a sometime basis, and that's mostly it. Would you say, from your experience with yours, that this is overstating the "limitations" of this ABC?

Last and least, can you close the dust cover on this BC? I've read that you cannot. The mfr doesn't seem to mention it one way or the other.

[SDW]

Oh, one more. Regarding the Bootleg ABC, the gas key screws are staked in an unconventional way. Like they just hit the tops really hard with a cold chisel. I wonder what's up with that.

[LRRPF52]

Thanks. So it simply restricts flow (as opposed to "dumping" it somewhere, somehow), like most adjustable GBs on the market. Interesting idea. It has four settings, one being specific supposedly to suppressor usage. Might be marked with an "S"? Is this setting the most turned down/restrictive of the range? Some of the opinions I've read state that with just four settings, as opposed to an "infinite" range of adjustment like an AGB, it's not the best device for tuning your recoil system to various ammo. It's said this the ideal application is confined to a rifle that wears a suppressor on a sometime basis, and that's mostly it. Would you say, from your experience with yours, that this is overstating the "limitations" of this ABC?

Last and least, can you close the dust cover on this BC? I've read that you cannot. The mfr doesn't seem to mention it one way or the other.

Most adjustable gas blocks use a small set screw to choke flow into the port in the block. You can see the set screw penetrate into the large port inside of the block. With most adjustable blocks, I've found that you need to allow the system to carbon-up before making adjustments, because there is leakage that eventually seals off, then the gas system gets additional flow into the carrier.

What has always bothered me is needing to cut a hole in the handguard or jimmying through vent holes for access to the set screw, which then carbon-welds anyway and is unable to be adjusted.

The Bootleg has an "S" position, which is the fully choked one. With the Bootleg, you have a mechanical advantage with the flat head driven adjustments, so I don't see it carbon-welding, especially being nitrided.

There isn't an infinite range of adjustments with set screw gas blocks, but a very defined and limited range where the set screw will intrude into the normal gas flow path up front. When fine-tuning a gas system, it's important to understand that you are fine-tuning for:

* The conditions you're shooting in, namely temperature and air density on that day
* The specific ammunition you're shooting
* The lubrication state of the action
* The cycle state of the action spring (new/worn-in well/on the edge of its life)

What I have found with adjustable gas systems is that you can find a setting that works great one day, a week, a month, 2 months, then all of a sudden, it doesn't. Then you go back to the set screw to wrestle with, hoping to find the happy window again. That isn't always the case, but will happen when you really try to dial it down for minimum reciprocating mass effects of secondary recoil impulse.

When I have been generous with the gas flow and leave it in place, they work fine year-round. That gas position setting won't be too far off I imagine from the positions on the Bootleg.

My ejection port door closes and stays closed.

[SDW]

Thank you for the thorough explanation. "Infinite" wasn't the right word to use. Maybe "analog" adjustment, vs.... digital, between all the way open and all he way shut. But having never messed with an adjustable GB I really don't know what they're like.

I'm tempted to ask, will a non-suppressed rifle run reliably on the "S" setting, but I'm sure there are too many other variables to make a sold determination w/o trying it. Probably safe to say that it'd cycle on the really "soft" side. And I assume the "U" setting at the other end is unrestricted completely, to behave like standard carrier. That leaves the two settings in between to play with.

BTW, on their site they describe it as, "4 Setting Adjustable Vent System relieves excess gas pressure created from suppressor use creating longer dwell time and less blowback..." which sounds a bit like a Pepto-Bismal commercial. Kind of funny if you think about it. But they do say it vents the unwanted pressure out somewhere. I'm tempted to buy one just to see how the thing works on my Grendel. (It's pure rifle in configuration.)

Oh, that thing about the cover not closing, might have been on a Gen1 version of this AGB. I read that the current ones are informally called Gen2.

[Klem]

The idea of carbon 'welding' or basically gumming up the mechanism as carbon accumulates in an AGB is real but can be avoided. Todd at SLRifleworks encourages turning their AGB closed after every range session. Clean it if you need to, and then open it again. It keeps cleaning fluids from leaking into the gas system but also cracks any carbon welding that has occurred. I use a long hex driver to adjust the AGB from the front and those two things eliminates 52's concerns about AGB's.

The Sentry 7 has 14 settings and I adjust as needed. One click further open solves the potential for stoppages caused by temperature, dirty parts and slightly different loads. As for the difference between suppressed and unsuppressed, that's a bolder adjustment of two to three clicks.

Whether an AGB is better than an ABC, I wouldn't know as I've never used an ABC.

[montana]

The idea of carbon 'welding' or basically gumming up the mechanism as carbon accumulates in an AGB is real but can be avoided. Todd at SLRifleworks encourages turning their AGB closed after every range session. Clean it if you need to, and then open it again. It keeps cleaning fluids from leaking into the gas system but also cracks any carbon welding that has occurred. I use a long hex driver to adjust the AGB from the front and those two things eliminates 52's concerns about AGB's.

The Sentry 7 has 14 settings and I adjust as needed. One click further open solves the potential for stoppages caused by temperature, dirty parts and slightly different loads. As for the difference between suppressed and unsuppressed, that's a bolder adjustment of two to three clicks.

Whether an AGB is better than an ABC, I wouldn't know as I've never used an ABC.

+1

I close the setting screw and re-set it every so often when I think about it. I have experienced zero problems for several years now. They sell purpose made long hex drivers, but I made several using wood dowels and old allen wrenches.

[SDW]

Hey LRRP52, How does the weight of the Bootleg BC compare to a standard M16 BC? I cannot seem to find that information online.

[SDW]

Hey LRRP52, I meant to ask earlier. How does the weight of the Bootleg BC compare to a standard M16 BC? I cannot seem to find that information online.

[Sixoeight]

Bootleg ABC acts like any other BCG, just with a restriction shaft with different openings to control gas flow into the Stoner Internal Expansion System of the AR15.

Excess gas is vented like any other Stoner BCG. Yes, I order them and immediately pull the 5.56 bolts out, to add to my parts box with countless other 5.56 bolts I doubt I'll ever use. (I have a lot of 5.56 rifles too.)

I believe it is not restricting gas into the expansion chamber but various setting of leakage to vent off excess gas. It would be pretty hard to restrict gas into the gas key from the location of the bolt carrier.

Just trying to clarify my previous post about venting vs restricting.

"The Bootleg carrier works by venting excess gas through the bolt carrier"
https://primaryandsecondary.com/gear-rev...t-carrier/

[SDW]

^^^ That's how the Mfr describes it too I believe. Dumps it out somewhere, like a turbocharger's wastegate. Either down, to the side, or straight out the back of the carrier. Since the gas is vented into the inside of the receiver somewhere, I don't quite understand how it prevents the "gas-in-the-face" issue. It still has to come out the ejector port, right?

[centerfire]

I have a few SLR gas blocks on rifles of various cartridges. None of them share the same gas settings and each has a different unsurpressed vs. suppressed adjustment scheme. Specifically the 5.56 and Grendel use different amounts of gas. None of them have carbon welded but there is some gas pressure difference between 30 degrees and 90 degrees, generally it's one click of adjustment. The AGB on the AR308 is buried under the rail but still easily accessible with an extended 2mm ball driver I bought on Amazon for $5. I run Sprinco red buffer springs in most of my rifles and the AGB allows me to adjust specifically for carrier and buffer weight as well as spring weight.

My buddy has a bootleg carrier that I've shot a bit, it seems like good quality but it only runs on two setting, U and S. The other settings simply don't function regardless of the ammo he's tried which is mostly M193 and M855.