I picked up a Sig 553 LB from JDI. It has a 13.66" one piece barrel and no removable flash hider to mount a suppressor. I prefer to shoot suppressed and was wondering if the Gemtech Halo would fit the Sig one piece barrel?

Anyone have any clue if the mount would fit the Sig?

This message has been edited. Last edited by: gw3971,

It will fit on the NATO-spec flash hider, but the "closer" will not work, as it isn't deep enough to reach the threads on the can, before bottoming out on the shoulder of the muzzle device. I have a 553LB with one-piece barrel, as well as a first-gen HALO, and GMT HALO. I can confirm that they do not work. The first-gen could work if you removed the barrel, and had a groove cut behind the slots in the flash hider, to accommodate the closer. The GMT, and other HALO-type cans, to include the Griffin GP-NATO, do not seat deep enough to even cover the flash hider's slots. There is even some bad info online about the HALO working on the 551. It doesn't. Unless that particular user had a 551 that somehow had a NATO-spec flash hider, which I don't think is a thing. Gemtech did make a HALO for the 551's smaller hider, but there are very few, if any, in the wild.

I have considered cutting said groove, or even having the barrel threaded on my gun, but have yet to actually make the leap.

quote:

Originally posted by KSGM:
It will fit on the NATO-spec flash hider, but the "closer" will not work, as it isn't deep enough to reach the threads on the can, before bottoming out on the shoulder of the muzzle device. I have a 553LB with one-piece barrel, as well as a first-gen HALO, and GMT HALO. I can confirm that they do not work. The first-gen could work if you removed the barrel, and had a groove cut behind the slots in the flash hider, to accommodate the closer. The GMT, and other HALO-type cans, to include the Griffin GP-NATO, do not seat deep enough to even cover the flash hider's slots. There is even some bad info online about the HALO working on the 551. It doesn't. Unless that particular user had a 551 that somehow had a NATO-spec flash hider, which I don't think is a thing. Gemtech did make a HALO for the 551's smaller hider, but there are very few, if any, in the wild.

I have considered cutting said groove, or even having the barrel threaded on my gun, but have yet to actually make the leap.

Thanks! guess I will have to wait and see if B&T releases a can that will work.

I highly doubt they will. If they could import, it would be a different story, but they can't. I don't think they'd bother tooling-up and building such a niche silencer in their US facility.

I tried a Halo-GMT and also another bird-cage can on my 551-2 Sport and also PE90 and no dice. The 551-2 has the short version and it fits but no slot to index on and the PE90 was too long. So, I just shoot my 551A1 or WCA 551 instead of the Swiss guns (or my 553 SBR w/ 8.9" 1/2-28).

Even if the 551 had a groove for the closer to grab, the OD of the hider is on the small side. It might work, but it certainly isn't proper. I don't think I'd be comfortable shooting it, and definitely wouldn't use it outside of a novelty context.

The OD's are not consistent. We checked the bore alignment and would definitely not shoot it even on the one that sort of locked in place.

Are those both 551s, in that picture? If so, I'd be curious as to the two different OD dimensions.

I know, for those NATO silencers to work, that OD should be around .864"

pre-ban 551-2 Sport and a JDI PE90

Ah. Gotcha. The ODs are consistent. That is, the 551 is consistent with other 551s, and the PE90 is consistent with the NATO spec. The way you phrased that made me think you were presenting two 551s, in which case that would have been the first NATO spec 551 I had heard of. I don't know why SiG opted to make the 551 different. It doesn't have enough barrel to launch rifle grenades, but I don't know why that would motivate them to make it a different OD for no apparent reason. Always thought it was odd and, in the case of using the NATO-spec silencers, certainly inconvenient.

Almost any suppressor can be fitted to almost any properly sized and threaded barrel. I wouldn't bother with anything Gemtech anymore as they are sinking since S&W bought them. Zero customer service, they don't answer their phones, or return calls or return email requests. There are plenty of NFA type machinists who can help you. Try the guy at Ecco first.
https://m.facebook.com/ECCOmachine/

I think the OP was wanting to mount a silencer to his 553LB without modifying it, which would necessitate the use of a "NATO mount", which is primarily produced by Gemtech and Griffin. The weapon in question has a flash hider that is machined into the barrel itself; it does not thread on and off like most guns.

I do agree with your assessment of Gemtech since S&W got them. I recently had an issue with one of my Gemtech silencers, and they wouldn't fix it. It sucks, because I consider myself a fan of Gemtech's earlier silencers.

I didn't have a 553 in front of me so thanks for the info.
The Halo was a good can but there are plenty of others I have that work as well. I like my Gemtech Shield with the bi-lug but have sold off most everything else except an Arrow with the nice Tri-lug for .338 Lapua and other calibers. The locking collar that slides back and forth is stuck in the furthest away from closing position and I have called, left messages, sent emails from my account and used Gemtech's own "Contact us" and have got Nothing in over eight months of trying. Ive posted on their website and their Instagram page, again with no success.
I will no longer order or stock anything Gemtech while I wait for the inevitable notice of closure.

OK Here goes. This is a comparison of an older 2004 build HALO with a newer 2013 build HALO.

First the '04 HALO:



Suppressor mount with the lock/tension nut. Notice the long length of the lock/tension nut.


Suppressor mounted and locked onto the muzzle of a SIG 551-2 SWAT. This is a factory SIG barrel. The suppressor mounts and locks snugly onto the barrel. The lock/tension nut covers the entire flash hider.


Suppressor mounted and locked onto the muzzle of a Colt M16A1 Carbine. This is a factory Colt barrel. The suppressor mounts and locks snugly onto the barrel. The lock/tension nut covers the entire flash hider.

Conclusion; The '04 HALO will work just fine on a SIG 551-2 SWAT and Colt M16A1 Carbine.

Now the '13 HALO:

Notice the suppressor mount with the lock/tension nut. Notice the short length of the tension nut.


The suppressor will not mount onto the muzzle of a SIG 551-2 SWAT. This is a factory SIG barrel. The lock/tension nut is too short and not screw onto the suppressor.


Suppressor mounted and locked onto the muzzle of a Colt M16A1 Carbine. This is a factory Colt barrel. The suppressor mounts and locks snugly onto the barrel. The lock/tension nut fits into the second Blank Firing Adapter ring and does not cover the entire flash hider.

Conclusion; The '13 HALO will not work with a SIG 551-2 SWAT, but it will work just fine with a Colt M16A1 Carbine.

Do you shoot your 551 much with that silencer attached? I have a Halo with the deeper pocket as well. It will "mount" on a 551. I don't care to shoot it though, as the OD of the 551 device is slightly smaller than the 22mm NATO spec, and there is a small amount of play when the silencer is not tight. If you look in the user manual of your older HALO, you should actually see that they make mention of the 551-specific model HALO that they apparently never mass-produced or made available to the public.

quote:

Originally posted by PGT:
The OD's are not consistent. We checked the bore alignment and would definitely not shoot it even on the one that sort of locked in place.

When SIG imported the 550s and 551s into the US they trimmed the diameter of the flash hiders. This was done so that a bayonet could not be mounted on the US imported barrels.

Back in the day, Gemtech made two different HALO suppressors; one to fit NATO standard diameter flash hiders and another to fit the thinner US imported SIG rifle flash hiders.

quote:

Originally posted by KSGM:
Do you shoot your 551 much with that silencer attached? I have a Halo with the deeper pocket as well. It will "mount" on a 551. I don't care to shoot it though, as the OD of the 551 device is slightly smaller than the 22mm NATO spec, and there is a small amount of play when the silencer is not tight. If you look in the user manual of your older HALO, you should actually see that they make mention of the 551-specific model HALO that they apparently never mass-produced or made available to the public.

I've never tried it with my 551 SWAT. I got my HALO way back when to use with my AC556K. A HALO on an AC556K makes for a compact full auto, silenced package. I had a conversation with Doc Dater about using the HALO on my AC556K and out of the blue he mentioned the update to the HALO for the thinner US imported SIG rifles. At the time I had no interest in using a suppressor on a SIG rifle. If I only would have known...

I didn't notice any difference in suppressor wiggle when the HALO was mounted on the 551 SWAT or M16A1 Carbine.

Why are current import 551s, and prior import LE/GOV't guns (which wouldn't have been subject to said bayonet silliness) also smaller OD then?

So your 551-2 SWAT is a NATO-spec hider?

quote:

Originally posted by KSGM:
Why are current import 551s, and prior import LE/GOV't guns (which wouldn't have been subject to said bayonet silliness) also smaller OD then?

So your 551-2 SWAT is a NATO-spec hider?

I have no clue as to both of your questions.