The first thing to do is to find a Class 3 dealer in your area. He might even be able to give you some demos of different cans and give some suggestions. I don't know what the laws are in PA for owning C3 items but that is something you can find out pretty easily.
I have heard both good and bad things about suppressing the FS2000. There is a member on this board that has had success with it and I am sure he will chime in. The first step is figuring out what to do with the barrel as it has a pinned FH on it. After you get that figured out the next thing is deciding which company and which mount you want to use. The AAC series is pretty proven and the M4-1000 seems like a good deal at the 500ish mark.
If you don't mind a thread on can there are a few options but really I think a QD is a better option. Again this really comes after you have found the comapny you want to go with. I know a couple guys that went with a gemtech g5 for use with the FS2000 and PS90. However there are still some doubts as to how much FA it can take. If you are buying it only for SA use then I am sure its a decent can. I am staying away from gemtech stuff until they explain why the G5 failed to supress flash and sound after a few hunrder rounds of FA.
Because of the length of the barrel its possible to use a SPR (AAC) can on it which is something I am considering. This design is supposed to be excellent suppression with less blow back to the user. Just know thought that you can't use the SPR on an M4 platform on anything shorter than 11.5 with a smaller gas block. Thats a tough sell when a lot of the people into NFA items use 10 inch uppers on the AR's they have.
Surefire is another company worth looking into and AWC has always been a quality company. Alothough many say they aren't keeping up with technology. Regardless of your opinion on this its still pretty hard to argue with a 500$ M4-1000.
One thing to keep in mind is thread on silencers are right out. whatever you use as a muzzle device needs to be pinned to comply with 922r so using a M42000 with a pinned QD flash hider is a good idea I used the Gemtech HALO silencer as it can be used on any of my rifles without replacing the flash hiders. and it works on almost any common flash hider. I have fired it along side my friend with his AR-15 equiped with the M42000 and the supression is almost identical. My FS2000 with the HALO is quiet enough to fire outdoors without ear protection but after about thirty rounds at an indoor range my ears were ringing
Here is a video of me fireing mine.
I'm working on this project as well. I'm going with the OPS Inc. 16th Model suppressor.
OPS uses as proprietary muzzle brake and barrel collar for their QD mounting system, so it's a little more complicated than some of the others, but from everyone I have spoken to, their quality is unparalled.
Adco firearms is going to handle the barrel and brake work necessary. I highly recommend them at this point as they have quickly and patiently answered the numerous questions I had regarding this project.
Thanks also to McGyver 007 for your detail on how to remove the barrel. It's going to save me having to ship off the entire upper for the work.
I have a QSM quick detach one and seems to work well but hard to say since not used another can on my rifle so I can't compare. The downside to my selection is I had to get the barrel threading redone so I could put a standard A2 flash hider on it. I guess the upside is anytime I used one of my friends AR15s I can just swap my can to their rifles.
Guys no need to reinvent the wheel I would go with AAC or Silencerco, silencerco has the brand new saker in production finally and their customer service is top notch. The saker has adapters for different brand flash hiders or screw on. You could also go with a 30'cal can like a sdn6 and use it on 308 and 223.
plenty of information on silencertalk.com.
I believe the FS2K is made in the United States. 922r does not apply. If it DID apply, the FS2K would not accept high capacity AR15 magazines. Look at the H&K USC and SL8: proprietary 10rd magazines. Same with the Saigas. You need to 'convert' all those guns to use hi-capacity magazines.