Is anybody loading the 450 SMC?  I am having a time finding brass so had a thought.

The firearm is a CMMG RDB 45 ACP setup, which is rated for the SMC.  

I have a good amount of 45 ACP small primer that I have culled from the herd, both nickel and brass, as well as small rifle and pistol primers of all varieties.

I think you see where I am going.  

Would it (small primer 45 acp brass) be up to the task, or do I have to resort processing 308 brass?  I'd like to build a 16" upper to go with my shortie, and the extra oomph appeals to me.

Starline makes 45 super brass would that work? You can also find once fired small primer 45 acp brass cheap (everybody hates the stuff ya know) I bought a big bag of federal small primer 45acp brass to make 400 Corbon. No idea it is is still out there.
There are some forums dedicated to the 45 super and 460 Roland that would probably have more info than arfcom.
Just sayin'

ETA;
There are some who say as long as you have a fully supported chamber you can use standard 45acp brass. 45 super brass is stronger and from what I can see 45 smc and 45 super are close with the super having higher pressure. So, as long as everything else is kosher you can use 45 super brass you just have to keep it at 45 smc pressure levels. Also it looks like Starline has new 45 super brass in stock. I am sure other places also have it, just have to look around a bit.

ETA Pt II;
Check the pressure levels for both. I have seen each one having higher max pressure. Who knows.

Uh, no, not really.  I've never before heard of 45 SMC.  What is it?  Is it a SAAMI cartridge?

450 SMC is basically 45 Super with small rifle primers.

This was my thought as well, but just looking for a little positive reinforcement before I dive in.

I am aware that there are likely more specific minded forums, but it is nice to banter about new topics here and there is a variety of experience in the membership to tap into.

Opinion time here. 45 Super was trademarked but not SAAMI approved. 450 SMC is basically the same thing but avoids that whole trademark thing. Neither have a SAAMI spec but there is a non-SAAMI set of specs (anyone having 300-221, 300 fireball, 300 Whisper, 300 BO flashbacks?) Boutique ammo manufacturers can and do produce to those standards but the big boys won't touch it with a 10ft barrel extension. It is scary enough that a rare round can be dropped into a 45acp and risk getting a new nickname of Lefty but add to that a very limited market, it just ain't worth it.
Anyway it is a fun round to shoot. Enjoy.

I use both starline 45 super brass, small primer and large primer 45 acp cases in my MK23 with no issues.

I frequently load 45 super/smc loads with standard small primer 45 brass....BUT I avoid blue dot and powder pistol.

Typically something slower like enforcer, 800x, longshot, etc.

These would be intended for a 16" barrel so I was thinking of something slower.  HS-6 I think would have potential.  You mention Enforcer, I have H110 which is "similar", but am open to procuring another propellant if it will improve performance.