need parts sources/advice on a dedicated 9mm build

[Shagnasty]

Going to be building a black creek precision reduced magwell 9mm SBR. I'm in need of advice on several things:

I need a good source for a 5.5 inch barrel. Right now I'm probably going with Adco but was curious if anyone had experience with Tactical Ambush firearms' 9mm barrel. The price point is almost too good to be true. This gun will be suppressed (Ti-rant 9) 80 percent of the time And I'm worried about zero shift. 1/2x28 threads a must.

Hoping to find a 4" free float tube with Keymod. I've seen the MAS defense offering and the consensus seems to be they are garbage. Am I going to be stuck taking a band saw to a 7" handguard?

Who makes good 20 and 32round colt pattern mags right now? Cprod and metalform are the only two that stick out in my mind, am I far off?

Since the gun will be for 100yds and in, plus I want to be as snag free and minimalist as possible, I am planning on running a Trijicon RMR. Can anyone suggest a good lightweight mount? Absolute cowitness is fine but I DO NOT want QD levers or thumb screws. Hoping to find something like the Daniel Defense Micro mount With its flush fitting flathead screws.

Now for the technical side of things: since a ramped bolt increases cyclic rate it stands to reason it decreases lock time, right? Should I just go with a 9mm hammer and a non ramped bolt to help reduce ejection port blow by? Or will the reduced stress on the pins be worth doing both? I plan on running KNS pins, an LWRC UCIW tube, slash buffers compatible 9mm heavy buffer, and a heavy spring. I feel like I'm over thinking this but since it will be a "for life" SBR I want to make it the best I can.

thanks in advance!

[halo2304]

From all I've read ADCO is good to go. I bought a QC10 5.5" barrel with 1/2"-28 threads. So far, not too bad, but I've also been trying to iron out an ejection issue. I've seen complaints about Tactical Ambush being slow to deliver. I've also read about MAS Defense parts needing some finessing with a dremel. They were samples of n=1 and YMMV, as they say.
As for a 4" keymod handguard, I'm pretty certain you would need to custom cut one. I had one cut from a Midwest Ind. rail. It came out pretty nice, but if I had to do it over again, I think I'd go with a quad rail as I had originally planned. With my handguard, I only have three slots and the rail stops pretty close to the last keyhole. The long term end goal is to add a finger stop and a VFG. As it is, I don't think there's enough room for all this and if there is, it's probably just barely. Careful component selection will be key. I should note as well, my rail came out to be 4.6ish inches long. Just enough that the threads are partially covered. I'm not planning to suppress it...yet.
Unfortunately, I can't give any insight to the rest of your questions.

[halo2304]

Here's mine, pretty much finished.
http://i42.photobucket.com/albums/e309/halo2304/Guns/20150508_120954_zpsoo9gcuqf.jpg