Hey all. Thought I'd share this link for a SBR to 1/2x28 thread adapter. P-90 Thread Adapter - $44.95 : Rock Creek Gun Service This is the adapter I used and after running it this weekend and confirming function. It worked fine as a stand alone with just the flash hider attached and it also ran completely fine with my Spectre II on it. It's cheap and the owner seemed nice when I spoke to him. I'm just posting this up as it seems this particular piece has been very difficult to come by lately for those of us doing SBRs on our PS90's.