PDW Caliber Choice.

[yoni]

Based on what worked for me, for a long time and in many different places.

I define a PDW as a weapon, that is shoulder fired but is still small enough to carry covertly and easily.

Examples are many, a lot of the B&T guns, MP5K Mini Uzi etc.

In order to qualify an AR would need one of the adapters that would allow a folding stock.

Then going up from the PDW we have the SBR/Pistol weapons with an 7 to 11.5 inch barrel. These weapons are easy to carry but harder to carry covertly. One of my favorite rifles in this group is my PTR in 7.62x39.

I have found in those times that I needed a PDW, regardless if I was on duty working covert or off duty caliber never played a part in the outcome. All my PDW's have been 9mm and a lot of times it was with ball ammo.

[mic2377]

Well it is all dependent on how short you want to go. Many have said this really well already.
4-7 inches - pistol caliber IE 9/40/45
7-10 inches - 300 BLK if AR platform, and 7.62x39 in some other one.
10+ inches - 5.56 or other variant cartridge. Actually if you run the numbers a 6.8 SPC is by far the most powerful and best ballistics of any SBR cartridge short of the 6.5 Grendel. Think a 90 grain Gold Dot at 2700 fps. It also has reliable mags and bolts.

[_Stormin_]

I have two opinions...

I love the 300BLK and it is great for a compact SBR/Pistol build. You pretty much need to be very well funded to practice enough with the damn thing. Ammo selection isn't the greatest but standard FMJs are holding steady at fifty cents a round or so. Then add a can and you're doing all right, though subsonic ammo starts to hurt the wallet in large volume shooting.

All of that considered, the MP5 (in SBR format) is still my favorite firearm currently. It's fast, it's accurate, it's absurdly easy to shoot, then put on the suppressor and load the right ammo... It makes it laughably quiet and never fails to make me smile. The B&T folder to the side, can off, and the thing fits into a laptop bag. I know there are more modern PDWs out there. B&T makes several of them. But the MP5 is my favorite. Then factor in the multitude of 9mm ammo choices and you have a round for just about everything.