I have found lots of data on the .40 S&W from a 4-inch barrel. But I can not find any data for a 16-inch barrel. What I am really curious about is how much velocity if any does an extra 12” of barrel add.

Does anyone know where I can find ballistic data on the .40 from a 16” barrel?

Or has anyone used a chronograph to measure how fast a 165gr. or 180gr. round comes out of a Sub2000 in .40 S&W?

I have seen no figures either, so my purely speculative guess would be that, since the .40 is "optimized" for handgun barrel lengths...much like the 9mm...you won't see much, if any more increase than with the 9mm rounds...maybe 125-150fps. There should be a fair amount of data out there on the 9mm from 9-16in. barrels from the sub-gun folks.

I agree with ikor. The powder burn rate of this cartridge is optimized for a fairly short pistol barrel and I wouldn't expect the see a whole lot of velocity increase. Also, I don't understand what the purpose is of shooting pistol cartridges out of long guns. Why not a rifle cartridge?

I own a Kel Tec Sub 2000.  The one I own shoots the .40S&W and it is made to use Glock 22 magazines.  The different versions of the Sub2K are made to use HiCapacity Glock, Sig, S&W, and Beretta magazines.  That the main reason this “rifle” shoots pistol ammo. Kinda like in the old days when cowboys tryed to match ammo of their long guns and pistols so they only had to carry one type of ammo.  In this case, one type of magazine.[):)]