I’ve got a transferable M11/9 on the way. I have a couple lage uppers for it. I’m also looking at building a Scorpion up for the GF.

I have a TiRant 45 I can use on these, but I’m thinking a dedicated can might be beneficial. I’d like to keep it shorter for a smaller package overall, but I could makeup the volume by increasing diameter.

I do not have a lathe.

Anyone done something like this before?

Wilson combat kinda has a 5.56 can like that, ask them

wilson

I haven't built one, but some parts makers have 1.75" tubes. I think the baffles will be difficult to supply unless you order it all from DM. I think a 5" 1.75"od would be nice.

Yes, but it won't work as well as a longer, thinner can.  While the pressure/volume calculations work out the same regardless of suppressor shape, it's not a closed system and there's a time component.  A 2" x 5 " can has basically half as much time to deal with the gasses as a 1.5" x 9" can, will not be as effective, despite having the same internal volume.

The larger the bore and the slower the propellant gas is moving, the more difficult it will be to produce decent sound reduction.  This is why 45ACP is generally a PIA to make quiet in a small package.

9mm is a bit easier but still not a simple thing in a short package.

Shearing or driving gas off the bore is the trick.  Length is always your friend.

I have an older 5.5 x 1.5 sdtac tube direct thread I use on my 9mm pcc. It's comfortable without hearing protection. I've never had it metered so I'm not going to say safe but no one around me is holding there ears either.
I'm not sure how short or fat you want to go but personally I wouldn't go less for my expectations.
If I were to build it again I'd probably go 6" or an recessed mount to get a little more volume.

I built a 5.5 or 6in 1.5 9mm 3 lug can. It is DM parts and a gemtech 3 lug. It sounds ok, it is comfortable to shoot without ears, but my trident 9 and tirant 9 are quieter. I am happy with it. It is usually on my full size mp5 sbr clone, and sometime on the k clone. It is all stainless so I could shoot 300blk supers through it if I needed, but I probably won't ever do that as I have a few 30 cal cans. I think it would have been better with the 1.625 or 1.75 tube, but I'm happy with it. Only thing I would change is maybe using all ti parts except maybe leave the first baffle stainless,  but it would have been a lot more expensive.

James