I don't recall.
You can find both types.
They have fake cans that will cover a 16" barrel to make it look like a short barrel with a suppressor on it.
Like this http://www.spikestactical.com/new/z/spikes-tactical-car2-fake-can-p-109.html
Or you can have a thread on fake can that threads on like a normal suppressor and have it pinned to meet the 16" minimum.
Like this http://www.spikestactical.com/new/z/spikes-tactical-et2-fake-can-p-110.html
Or, if you like the look of Dustin's, you can get an SD which is a shroud.
Basically just .5" longer to give a little more to fit up under your rails.
http://www.spikestactical.com/new/z/spikes-tactical-sd2-fake-can-p-44.html
WMD, thanks! Just what I was thinking of. Good to know I could go either way.
Something about pinning a 9mm AR barrel;
The bore is .380"-ish. The od at the threaded end is under .500". That's .120" left for the barrel, which is actually less than half (.060") material, figuring for thread depth, rifling, and that .120" make up two sides.
Originally, when I was gonna make my pistol a rifle, I considered making an extra long flash hider, like the Bushmaster Commando, or whatever they call it, but with 1/2-36 threads. I ended up finding one already made for $25. A RRA 10.5" barrel is actually longer. Not sure why the advertise it that way. Measured from the bolt face, with a 5.5" FH, it is just over 16". The problem is, there is not enough meat there to do a pin/weld job. I called the local BATF, who referred me to a NFA guy at the big office. He explained other methods of attachment, one of which is high temp solder (it's a specific solder, so look it up if you go that route) on the threads, or a big weld. He explained that if the weapon was to come in to their possession, they put the upper in a barrel, and place a big pipe wrench and twist away. If it comes loose, it wasn't permanently attached. He said a lot of pinned jobs don't pass, and agreed on the weakness problem of the end of the 9mms. I ended up welding mine externally to the underside of my barrel with my TIG. It's a little longer than a 1/4", and is under a MI SS10 handguard, so you can't really see it anyway. It is significantly stronger than any small pin, keeping me legal and safe.
Just my two cents.
Here is the guy I got the FH from;
Garrison Mfg. Inc.
P.O.Box 231
Wauseon, OH 43567
419-392-2542
If you get one, and want it welded, PM me. I'm happy to do it, and it's free.
My RO635 was approved yesterday. Pics to come. 
I am a happy boy today.
I am a happy boy today.
My RO635 was approved yesterday. Pics to come.
Probably the coolest ever. Are you gonna leave the furniture alone, or *******ize it?
Once you have it, is the 9mm SBR the ******* child that is abandoned, or will you still love it like you did?
When you have grown tired of it, you can give it to me. You are too busy threading to shoot it anyway. The SMG, I mean.
I'm extremely torn. I originally planned to strip down the receiver and build it up with my SBR parts so it was effectively my SBR with a fun switch. But the closer it gets, the more I want to leave it alone. I guess I could build my SBR back up with the Colt parts and have it that way, but I just don't know. This is going to be a tough decision. I will probably remove the mag adapter and use my Hahn so I can easily swap the uppers to shoot 5.56 too. I just don't know yet. We'll see when she comes in. I have to at least wait until after the demo for the department. They want to see an RO635.
Just keep your upper and slide on stock from the sbr, put it on the SMG when you get the urge (probably most of the time?), and put your 5.56 on the SBR. Oh, wait, you mean the Hahn block in the SMG. That makes sense. SBR, SMG, OMG, WTF???
I think the bolt is unramped for your RO635, so it seems like buying a ramped bolt would be a wise move, as not to alter the original (you know, by machining it).
When you have the original upper on it, it is morally imperative that you sling it "commando" style, with a GI black strap, with tape covering the adjuster hootises (what's the plural for hootis?).
I think you need a DEA upper for it too!!!!
