Suppressors that mount on A2 flash hiders

I watched a video on YouTube that demonstrated the B&T Rotex X suppressor. The most interesting thing about this suppressor is that it mounts directly to A2 flash hiders. To me, this seems way more desirable than having to buy a special muzzle attachment for each rifle that I want to use a suppressor on. Honestly, I'm surprised that I have not heard about it before now. For those who are familiar with it, are there any downsides to this suppressor attachment method? Besides B&T, are there any other suppressors that use the same attachment method?

Gemtech HALO series was made specifically for use with A2 flash hiders, and have been around for decades. Griffin Armament has had some options for years, too.

The A2 was never designed to be a suppressor mount, so it ends up being a poor suppressor mount. You generally do not get a repeatable POA/POI shift, which can be several MOA. Most A2s are mounted with crush washers and not machined to very tight tolerances, so misalignment causing baffle strikes is much more of an issue. Dedicated suppressor mounts are a thing for an actual performance reason.

I see zero reason to use an A2 flash hider as a suppressor mount outside of some kind of institutional reason. The idea of being able to use your can between multiple guns just doesn't make much sense to me if you're using it for any kind of serious purpose, given the changes in POA/POI between suppressed and unsuppressed (especially if the shift is inconsistent), to say nothing of some of the optimization you might need to do to each gun if using a high backpressure can.

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Originally Posted by Defaultmp3

The A2 was never designed to be a suppressor mount, so it ends up being a poor suppressor mount. You generally do not get a repeatable POA/POI shift, which can be several MOA. Most A2s are mounted with crush washers and not machined to very tight tolerances, so misalignment causing baffle strikes is much more of an issue. Dedicated suppressor mounts are a thing for an actual performance reason.

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I was hoping that there wasn't a downside, but thanks for explaining.

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I see zero reason to use an A2 flash hider as a suppressor mount outside of some kind of institutional reason. The idea of being able to use your can between multiple guns just doesn't make much sense to me if you're using it for any kind of serious purpose

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I wouldn't be using it for serious use. I'm primarily a collector, so keeping my rifles original and minimizing the cost of trying a suppressor on each of them is appealing.

I disagree that they don’t work well as mounts. I’ve got a M4SDk, 30SD, M4SD-L (jail), a Griffin Gate lock adapter on a Turbo K. You remount the A2 using shims instead of crush washers, so that’s not a real problem except for institutions where policies are written by dumbshits. Griffin makes two cans specifically for those institutions, only one of which is in the consumer catalog. However, if you find yourself working in suck a moron-laden organization, you can also use one of their Gatelock or Nato adapters with a grossly overbore can, like a .358 or .458 MG7k. Which is probably a good idea, since the meatheads that disallows the armorers replacing a crush washer also won’t allow the armorers to dick with the gas drive.

The Halo style adapter has poor RTZ due to having no rotational indexing other than trying to put it on the same way each time.

For a precision rifle, use some sort of taper mount.

KAC NT4 mounts on a mount that mostly looks like an A2, but isn’t. It won’t mount on an A2, due to the indexing notch. The Griffin Gatelock cans index off the wrench flats to avoid that.

Wilson Combat A2s consistently work well with Griffin cans and adapters. Other brands are sometimes out of spec in diameter, oversized (I measured with a micrometer based on the .mil TDP), preventing mounting.

Of the natively A2 mounting cans, the 30SDk and M4SD-L are probably the best choices.

You will get some soot on your glove if you shoot a lot and your rail runs all the way to your can, but it doesn’t seem to affect sound or cause carbon lock, with the Griffin stuff. The NT4 will definitely carbon lock, but that’s why it’s indexing notch is angled.

An A2 mountable can does have some appeal for someone like me who hates suppressors on ARs, but would like to have a quick option if needed. Wasn't AAC's version the "Omni"?

I appreciate all of this information. Would an alignment rod be the ultimate verification test?

A2 mounting systems are longer and heavier than most any other mounting systems. Significantly more than the great taper options that we have now. At least choose a HUB option so you are not stuck with the A2 mount like in the old days.

At a minimum you need to remove the A2 and crush washer, then re install with shims. You should also probably measure the A2 and make sure it is within print.

At that point how much harder is it to try out on multiple guns with a direct thread base or one adapter of whatever mount system you choose?

A lot of people fret about the cost of adapters for every gun they own, then end up dedicating a silencer to one or maybe two guns.

Does anyone make an adapter allowing the HALO to use another mounting system?


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Originally Posted by Todd.K

A2 mounting systems are longer and heavier than most any other mounting systems. Significantly more than the great taper options that we have now. At least choose a HUB option so you are not stuck with the A2 mount like in the old days.

At a minimum you need to remove the A2 and crush washer, then re install with shims. You should also probably measure the A2 and make sure it is within print.

At that point how much harder is it to try out on multiple guns with a direct thread base or one adapter of whatever mount system you choose?

A lot of people fret about the cost of adapters for every gun they own, then end up dedicating a silencer to one or maybe two guns.

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I agree. The Gatelock adapter adds almost the same length as Keymo or YHM original; 1/4” less, though the mount + adapter total weight is noticeably lower. The Nato (Halo style) adapter is even longer. Because of that, I’d make the opposite recommendation: if you want an A2 can, get one that uses the system natively. Just like if you like Keymo, get a Sandman S.

The M4SDk or Turbo K with adapter adds 4” vs a bare A2. So an 11.5” gun with silencer is about the same length as a 14.5” P/W, and a 12.5” with silencer is 3/4” longer than a 16” with an A2.

The benefit vs a simple taper system (which I also highly recommend) is that there are no exposed threads to protect when you shoot without it, and it weighs less than other Hub systems with that same virtue, and probably costs less in total, also. So if your host weapon doubles as an unsuppressed work gun, or a 3 gun rifle with a brake getting banged into barriers, then it should be given strong consideration. Think of it like a Keymo that weighs less and doesn’t have ratchety teeth to wear out. It also self-clears sandy debris when attaching, like the NT4, rather than allowing a large grain of sand to get sandwiched between the tapers like a Keymo.

I haven’t found an undersized A2 or A1 yet. So far the only reason to mic them and compare to the drawing is curiosity, for me. Every one of a dozen or more commercial A1/A2 flashhiders that I’ve tested has been in-spec if it fits inside the can and allows the gate to close. I’ve checked some military A2s also, and 100% of them were suitable. As to which spec is wrong on some commercial ones (and FCD 6315), the most common problem is too large OD to fit in the silencer. The other problem is too narrow of a BFA groove, which is much less common and doesn’t allow the gate to close. You know more than I about this…can both of those be attributed to cheap manufacturers not changing out tooling often enough?

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Originally Posted by Bret

I appreciate all of this information. Would an alignment rod be the ultimate verification test?

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Probably. I haven’t found one that failed that yet, though. I was a little nervous putting a gatelock adapter on my Turbo K because it has a fairly tight bore, but it turned out to be just fine. Of course, it also added an inch.

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Originally Posted by Defaultmp3

Gemtech HALO series was made specifically for use with A2 flash hiders, and have been around for decades. Griffin Armament has had some options for years, too.

The A2 was never designed to be a suppressor mount, so it ends up being a poor suppressor mount. You generally do not get a repeatable POA/POI shift, which can be several MOA. Most A2s are mounted with crush washers and not machined to very tight tolerances, so misalignment causing baffle strikes is much more of an issue. Dedicated suppressor mounts are a thing for an actual performance reason.

I see zero reason to use an A2 flash hider as a suppressor mount outside of some kind of institutional reason. The idea of being able to use your can between multiple guns just doesn't make much sense to me if you're using it for any kind of serious purpose, given the changes in POA/POI between suppressed and unsuppressed (especially if the shift is inconsistent), to say nothing of some of the optimization you might need to do to each gun if using a high backpressure can.

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I've been running HALOs from the beginning (early 2000s) and never had a problem. Running strictly on Colts for the most part, zero issues...consistent POI.

It's one of the few cans that works on my HK93s and the only can that works on my SIG 550 and 551.

I've run them on select fire M16A2s, select fire M4s and 11.5 and 10.3 semi autos. Never a problem. If they get very, very toasty the expanding metal will lock them in place until they cool down enough to remove.

Honestly the mounting system isn't dramatically different from a SF suppressor.

The only "issue" I noticed is running them on a Colt 6520 which is a 16" pencil barrel, with a steel HALO (they now make titanium), you do get some barrel whip that opens up the groups a bit but that would happen with any can of the same weight.