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What are the options for suppressing a swiss SG550/551 in USA Login/Join 
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so from what I've read older gemtech halos can work for fixed flash hider models with an OD of 22mm. Is this still the only method for using a silencer? can the 4-pos 553 gas selector be used for 551 or 550 or would they require their own specific gas selector?

are certain barrels more guaranteed to work than others (ie 551-2 sb barrel vs 551-1 sb barrel).

I would like to use a silencer with my JDI sg550p, and a 551sb variant. Didn't jdi mention some type of partnership for silencers to be made here for these or is that vaporware.
 
Posts: 3 | Registered: October 12, 2021Reply With QuoteReport This Post
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As far as I know, there is no 551SB that has a 22mm flash hider. So, despite what you may read on various forums, the older HALOs will not work on a 551SB. You aren't going to suppress your 551SB without removing the barrel and having it threaded. From what I have seen, in my experimentation, I suspect that the very few HALOs that were supposedly built for the 551 didn't really work all that well, due to the taper behind the muzzle device. An older HALO will not work on a 550 without removal of the barrel, and modification of the groove behind the flash hider slots. Either way, all this requires that you have an older HALO; if you don't already, you'd be quite lucky to find one.

The SAN 4-pos valves will not work on a 551 or 550, because the OD of the piston is smaller on the short gas system guns that those valves are designed to work with. Custom valves are doable though.

As far as I know, despite what you read, all 551SB barrels are the same, and none of them are 22mm at the flash hider.

Either of the guns you're asking about would be best-off being threaded by a competent gunsmith, if you want silencer compatibility. If you have an older HALO, you can retain some originality on the 550, by only modifying that groove. Keep in mind it has to be the HALO that is compatible with the Smith Vortex flash hiders, for the pocket to be deep enough to cover the flash hider completely.

I am unsure whether or not JDI mentioned any kind of silencer partnership. The only thing that is often cited is B&T, but even they don't have one for the 551, and aren't making rifle cans stateside yet, as far as I know.

Everything I have to say on this subject is based on experience. I have 553s, 551s, and a 553LB (same barrel profile as 550), and I have invested much time, and plenty of money, in experimenting with suppressing all of them in the best way possible. If you have more questions, I'd be happy to answer them to the best of my ability.
 
Posts: 311 | Location: Northeast GA | Registered: February 15, 2021Reply With QuoteReport This Post
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So if i don't want to alter barrels I pretty much have no option unless someone comes out with something that works with the internal threading..?
 
Posts: 3 | Registered: October 12, 2021Reply With QuoteReport This Post
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Correct. I think it's pretty unlikely that something utilizing the internal muzzle threads will come around. If it hasn't happened by now, I don't think it ever will. The 551 seems to have been largely replaced by the 553 and 553LB, by any organization or agency that cares to use a 550-series weapon. The 550 is obviously still in use by the Swiss armed forces, but they don't seem in a hurry to suppress infantry rifles. There is a thread somewhat similar to this a little ways down the page, in the suppressed weapons forum. The OP of that thread ended up having a barrel I didn't know about, which would actually likely work with a few available silencers. In the interest of covering all the bases, I'd encourage you to look at that thread; there's always the chance that your 550 barrel is of the same design as his 553LB's.
 
Posts: 311 | Location: Northeast GA | Registered: February 15, 2021Reply With QuoteReport This Post
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the internal threading is for a blank firing adaptor, not a suppressor. If you want a 551 to run suppressed, you either need to chop/thread the 14.3" barrel or you should look for a 16" 551A1, West Coast Armory/Sig 551 or a normal 556.

The 552 and 553 were designed to run suppressors...the longer iterations were not so cans were an afterthought.

I tried a newer Gemtech Halo on both my 16" 551-2 and my 550 and as KSGM has said, no dice.
 
Posts: 2472 | Location: Leesburg VA | Registered: December 21, 2014Reply With QuoteReport This Post
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my 550 barrel is a 1 piece hammerli. It definitely won't work.

In europe there are silencers available for the SG rifles that work with the internal threading, http://saimaastill.fi/portfoli...uppressor-rk-series/

and I believe sig sauer AG lists silencers for them in their catalog as well.
 
Posts: 3 | Registered: October 12, 2021Reply With QuoteReport This Post
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Ain't that some shit. I wish they had more images of those silencers. I am curious how they seal off the flash hider slots; if they do it internally or externally, and I wonder how they make up for the difference in OD between the two guns. Either they seal internally, or there is some kind of swappable piece. I can't seem to find a single image of one on a Sig rifle of any kind. Unfortunately, the chances of seeing one of those cans stateside are slim to none; if B&T hasn't decided to produce the ROTEX here yet, we're still a long way off for other fancy European rifle cans. The trouble with the Sig rifle aftermarket, is the demand isn't quite high enough to make it worth most manufacturer's while.

I think all the silencers in the AG catalog are B&T types, not necessarily intended for the 551 and 550. I'd take their catalog with a grain of salt anyway, as the one's I have seen are riddled with grammar errors, typos, and other silliness. It wouldn't surprise me if they just stuck a picture of a silencer with every weapon accessory list in there. The 553 in .300BLK has a barrel contoured for use with a dedicated reflex-type silencer. The US market will never see that can, so folks are just irritated by the barrel length and contour, and chop them down.
 
Posts: 311 | Location: Northeast GA | Registered: February 15, 2021Reply With QuoteReport This Post
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