While I was there, they had an OSS MR 556SD on an HK AR15, which I got to fingerbang. Pretty cool looking but just too much stuff going on for a suppressor in my opinion.
They also had a Heizer Defense PAR1 Cal. 223 single shot. That was, interesting to say the least. The trigger is junk (literally an inch and half of play) built in iron sights and it kicks like a mule, but if you want to shoot a single .223 round for whatever purpose this is your pistol.