I’m going to purchase my first sound suppressor soon. My go to gun is an M4 clone that has a 14.5” barrel with an extended A2 flash hider that I pinned and welded. I remember when the Gemtech Halo used to be advertised to fit any NATO flash hider(even the longer HK93 flash hider) so I assume it utilized a collet-style fitting for attachment. From what I’ve read, the Halo looks like it only fits a standard A2 now? Does anyone make a suppressor that will for standard A2 and extended A2 hiders? Thanks in advance.

ARKAR

Griffin sells an A2 mount adapter that fits any suppressors with Omega compatible mounts: https://www.griffinarmament.com/a2-adapter-for-1-375x24-suppressors/

That should work with an extended A2

That's milspec a2 not the longer a2.

Would there be any concern with how the flash hider was mounted? I know with the Gemtech Halo they emphasized that the A2 flash hider needed to be shimmed. I would imagine that would still need to be the case even with a P&W A2 flash hider.

I just read the owners manual on the Gemtech website and you are correct. The flash hider needs to be mounted using shins to insure the hider’s blank firing adapter groove is perpendicular to the bore to prevent baffle strikes. I could remove the weld and remount the suppressor with shims then repin and weld but I’m still uncertain if the suppressor will accommodate the longer hider since the distance between the BFA grove and the end of the hider is longer on the A2X.

Regardless of what can you go with you'll want to remount with shims to assure that things are lined up correctly. One option would be to go with a Griffin M4SD II, Griffin M4SD-K, or Griffin M4SD. Since you'll be doing an R&R of the MD anyway, I'd go with a Griffin Gate-Lok MD as well. These are just as long as the A2x or longer so you'd easily bring your 14.5" barrel to 16+.

Another option that you have since you need to R&R your MD would be to move to a taper mount. This would open up your options on cans quite a bit. That of course depends on if there is a specific reason that you're running an A2x in the first place (such as atheistics).

ETA: The 1.6" OAL of the A2x shouldn't be an issue w/the Griffin cans and/or adapters. However, some specific MDs aren't compatible due to the spacing of the slots. The BCM A2x is an example of a non-compatible MD.

I own the GMT-Halo, actually it was my 1st suppressor purchase year ago. Straight from the owners manual:

"For there to be proper alignment, it is essential that the compensator
backs against a surface that is 90° to the bore axis. Any washer that does
not have perfectly parallel sides will tilt the compensator. Lock washers and
crush washers cannot provide parallel sides and will always result in
misalignment. For this reason, a shim washer set is included with the
suppressor for proper clocking of the flash hider (compensator). If the compensator
is already mounted with a peel washer, there is no need to remount."

Basically NEVER use a crush wash. We all know that. Truth be told I've used this can on multiple hosts (before I dedicated it to one) and never had any issues.

I have it dedicated to an 8" 5.56 host (I know, heresy.. lol!) using an AR Stoner A1 birdcage that's using NO SHIMS for timing. Rocksett & torque the MD right to the barrel. I've had it in this configuration for over a year.

Also, along the way I've used the GMT-Halo mounted to 2A Armament T3 compensators without issue. The suppressor collar engages on the 1st ring, not the 2nd ring like a normal A1/A2 MD.

So in a nutshell OP, this may work on your extended MD on the 1st ring. I can't vouch for that but it might.

Okay, I need to clarify..

My above rambling is pertinent to a GMT-Halo only. Truthfully, there's no way I'd suggest buying one of these in today's market. They're an oddball to say the least.

As long as your extended A2 is pinned/welded without a crush washer (which it should be,) you can use the GA system posted above and procure whatever suppressor you want that uses the new 1.375x24 mount system.

Heck, I'd buy the GA system and mount a YHM Turbo-K on it. Cost effective, and works great. I own 2 Turbo-K's.

Before you go through the trouble of remounting, I would mock it up.  

Get the Griffen A2 adapter, borrow a suitable suppressor (usually means going to the FFL dealer and making friends) and pass a alignment rod to check concentricity.  

You can also get a mock suppressor to check.  

You won’t know until you do all that, and that means (most likely) you’ll have to buy the pieces just to get to that point.  

I routinely recheck suppressor alignment.  

I done exactly that, and the only difference is the use of an extended A2 vs A2.

You can buy much higher quality crush washers that will have a higher tendency to crush with uniformity.  Almost to a point of being perfect every single time.  

I absolutely do not care, nor will I get into a theoretical debate if that is true or not.  Do or don’t, I don’t care.  

I’ve used them and checked alignment for years prior to shooting and it’s always been perfect.  There is always the chance the next time the alignment will be off (due to previous barrel heating and cooling) but after years of doing this, it’s always been perfect.  I’ll still check alignment next time.  

There are many other people with the same experience I have.

If you are open to re-pinning the muzzle device, then definitely look at other attachment methods and muzzle devices. You are going to be locking yourself into one attachment method, so you might as well be happy with it instead of settling.

As for the crush washer debate. My brother in law, who failed to consult with me first, mounted his muzzle device with a crush washer. The alignment was fine for almost 3 years and then suddenly he started complaining about a massive POA/POI shift. I checked the can and barrel and found that they were out of alignment, which caused his POA/POI shift. Luckily it was caught before he put a round through the end cap. I remounted the muzzle device using shims and everything was back to normal. YMMV, but I would never use a crush washer on a muzzle device that was going to mount a silencer.

Just don't.

Personally, I'd just sell the 14.5" upper and build a new upper with whatever muzzle device you decide on.

Yeah, I don't understand this. If you get a good and straight alignment rod, check the suppressor alignment. If it is straight and the mounting is secure, why does it matter if shims or washers, or whatever were used?

Obviously, if the alignment rod is not centered, then you have a problem and that needs to be fixed, but if it is centered and the mount is secure, then why start taking stuff apart and fixing things that aren't broken?

The extended flash hider might cause trouble with cans that are designed to mount on A2's. I'm pretty sure the extended ones wont work on my Griffin M4SD2. Yes you should have shims, not a crush washer. Although if you can line up a rod from chamber to the tip of the can with no problem, because its pinned on, it MIGHT be ok. Honestly, I'd suggest removing it and using shims. And if you're going to go through the trouble of removing it, I'd recommend using a normal A2 along with an ADCO spacer. This spacer goes behind the FH to push it further out and will get you 16" with a standard A2. Yes, it gives less threading that the FH will secure to, but its not a problem if it is pinned in place. This will let you mount suppressors designed for A2s and this is exactly what I've done on my 14.5". If you go this route, some A2 FHs by various manufactures are not all to proper spec and may not fit cans like the Griffin. I'm running a BCM A2 and it works great with my m4SD2 can. If you go with a griffin, you'll want to remove the muzzle device anyways to mount the overtravel stop along with the shims.

Thank you for all the input everyone! I’ve just about decided to go with a suppressor that uses a proprietary muzzle device for mounting of the can. I will remove the A2X and mount and pin the muzzle device with the correct shims.