To start off let me say I have a stamp in hand, I have built cans in .556, 9mm, and .30 cal.  But what those were more what I would call normal builds, standard length barrels for the rifles for example.  What I'm wanting now is a can to go on a 12.5 .308.  It will have an adjustable gas block.

So what I'm asking is what would you suggest to do differently from a 308 can that would go on a 18" barrel?  My plan right now is to make a direct thread can with an integral muzzle brake in the rear cap.  I'm trying to keep the overall length of the weapon down as much as I can and I expect this can to live on this SBR.  I'm thinking of 1.625"OD titanium tube and SS baffles. I have both 17-4 and some 422 stainless bar, I also have titanium bar so some baffles farther down the stack could help with weight possibly although I dont think it will make a great difference in weight.

Design wise, it appears cans like the Razor have a large expansion chamber, I think this might help with the issue of blowback from such a short barrel.  

thoughts I'm considering and would like your thoughts on:
*around 7 baffles with equal spacing after a large blast chamber
*progressively smaller bore starting around .422" near the muzzle to help with backpressure
*possibly going to a larger tube such as 1.75"

Love to hear your thoughts on what I have in mind as well as ideas to make it better

What I'm after is a handy short overall length hunting rifle.  This will be with full power ammo. I'm hoping to get decent suppression, I know it won't be hearing safe since it will be on an AR gas gun. I dont want an anchor hanging on the end of the barrel.

Ideas and thoughts?

Maybe consider if you can reflex part of the blast chamber over some exposed barrel.  Something like this part plus an integral brake:

https://quelltech.shop/product/asr-otb/

Might want to have a narrow, unclipped (but maybe drilled) flat baffle in the front of the stack to catch the brunt of the burning powder out of that sbr.  Make a second one and use it as a spacer at the end cap of the can.  Once the first one in the front is eroded, swap the front and back to extend the life of your can?