Suppressing San Swiss 550, 551P, 553, and 553 R

[KTR03]

Hey There,

So I have some questions regarding suppressing swiss rifles. I have a 550 SP2, and a 553 in .556. I also have paid for a Sig 553R and a 551 pistol. The latter two should both be here in the next couple of months.

I am unclear on whether the 551 will come with the traditional integral flash suppressor, or a conventional screw on type. IF the suppressor is integral to the barrel, what are my options for suppressing the 551? I have heard unconfirmed reports that the Gemtech Halo will work. I also have read something about a B&T suppressor that can be mounted using the internal threads of the flash suppressor. NO idea how any of that works. Also no idea if B&T or any other can for that matter, can be imported. Does anyone know first hand whether this is doable? Also does San Swiss make a 4 position gas plug for the 551s like they do for the 553? Ideally I'd like the capability of throwing the can on the 550 as well, but more as a contingency, not as a full time thing. The rifle is damn long already.

On the 553 in .556, I have a AAC 51t mount they I intend to mount on it. I have also read that doing this will prevent the removal of the gas tube. True? Can it be shaved down to allow the gas tube to clear without affecting the mount? On the 553R, the barrel is long enough that I don't see an issue on that one.

Any substantive input would be great. JoshNC? Others who actually own these guns? Please don't answer with Sig 556 info or an argument about why ARs are better...

Be Safe,

[JoshNC]

I don't believe SAN makes a suppressed valve for the 550/551, only the 552/553. There was a guy on one of the other forums making suppressed valves for the 550/551/556, but I don't recall which forum. The Gemtech HALO is supposed to fit the 551 short barrel, not sure about the 550 as I think (may be wrong) the 550 has a slightly smaller OD on the flash hider than the Stg90, PE90, and 551 short barrel. I personally would not mount a HALO on my Swiss SIGs, as it will undoubtedly mar the finish on the flash hider. That's fine on a post sample fullauto work mule, not so much on a highly collectible Swiss rifle, especially a pre-89 import.

I don't believe B&T ever made a can that mounts to the internal FH threads. I believe it was a Finnish can, maybe BR Tuote. In any event it doesn't matter because imported title-2 is verboten for civilian commercial sale. You could have someone make you an adapter to use with one of the modular 5.56 cans on the market. I suspect Dead Air or similar could accomplish this for you. Again though, a portion of the can/mount will likely have to recess over the flash hider, which will mar the finish.

Re: modifying the gas tube to allow removal with an AAC or other suppressor mount FH attached, it *may* be possible. The 55x variants for german commercial sale have/had a heavy barrel which required that the front collar on the gas tube be relieved on part of its circumference. I used to have one such gas tube for a 550, but sold it long ago. You're pretty close to Estes, I would drop in and ask him about this. He can prob also make a suppressed valve for the 550/551 from a standard valve. Should be pretty easy.

I personally gave up on shooting my Swiss SIGs suppressed. They are already heavy without a can. When I have used a can on one of my 552s (AAC M42k) it was VERY gassy. Maybe use of a suppressed valve would change my impression. I simply lost interest. Now, when B&T USA offers a domestically produced Rotex-V I will use that on my 552 and 553. No word on timeline.

[SteyrAUG]

I can confirm the HALO works on PE90 and 551 firearms. Suppressor setting valve doesn't seem necessary.

http://i.imgur.com/dCTa9L0.jpg