Stupid ass questions I know

1* .40 rounds fit in .45 mags? (Lwrc Sub 45 with ump .45 mags)
2* I am going to guess that the (KA) MK 23 suppressor fits very few guns and would not fit the above gun?
3* I don't know what ***The Mk23 USP silencer will work on any .45 caliber 16x1LH barrels*** means really. I guess 16x1LH means the threads are either close or further apart then what 99% of other hand guns use and If you want to use it for a glock or in my case a Sub gun I would have to use a custom made barrel?
4* I work off shore so when I go to shoot I shoot alot and don't slow down and I was wondering if a all S/S tube would hold up to the heat better then a aluminum tube if you are just going to blast it all day with a binary trigger.

Not sure how many rounds you would have to dump in one go on a aluminum tube can before you had to take a break? Any ideas?

Why are you wanting to use the KAC Mk23 suppressor? There are better cheaper options available now. The only real reason I'd see getting one would be to complete a Mk. 23 in the first place. Aside from that, I'm sure .40 would physically fit in a .45 mag, but it's not going to feed right at all. The 16X1 LH is the thread pitch of the suppressor, and yes it's not very common in a lot of firearms that I'm aware of. Again, the Mk23 and suppressor were really meant to be used together. Newer suppressors have swappable pistons of different thread pitches which allow them to be used in different firearms.

As to durability, I really doubt you're going to shoot out a modern name brand pistol suppressor, given both the durability of materials and pressure of handgun rounds. If you did, I'm sure any reputable manufacturer will take care of you (I know silencerco will, and I'd wager others will as well). I'd suggest you read up on the suppressor forum, and look at options like the Revo, Osprey, Obsidian, Ghost, and other modern cans that are cheaper, give better db performance, lighter, and more adaptable.

Dude don't give bad dope.
The mk23 is threaded 16x1 Right Hand! The USP tactical is 16x1 left hand. So if you buy the knights mk23 can there is nothing compatible with it. The knights USP tactical is in the more common 16x1 left.
Ad mentioned, they're older technology and heavy. It's great if you're a collector but not very compatible with other platforms. I'd suggest looking at the silencerco octane, they have pistons for both 16x1 left and right, and also  are compatible with .40 and 9mm. A lot cheaper too. The baffles in the octane are removable and easy to clean. And it's full auto rated so mag dumps are gtg.

Oh shoot yes, didn't catch that, my bad! Yes HK uses both 16X1 LH, and 16X1 RH, which is annoying.