If you're not stuck on 5.56, 300 BLK is also a great option for short ARs. Even out of an 8" barrel, it's still a very potent round. 110gr at 2,100 FPS. That's more energy than a 5.56 will have out of a 12-13" barrel.10.5 with a 5.56 - shooting full house 5.56 and not watered down stuff (check out Brass Facts on YouTube for some eye opening data about factory "5.56" loads not being loaded to full power) you're going to have a short distance where the round will perform as designed / intended. Beyond that, you'll not get the wounding potential the round is known for. This may or may not be a concern to you, and a hole is still better than no hole, all things given.
That said - a 10mm with full house loads is no slouch and the lethality is nothing to scoff at.
The UMP and a short AR have overlapping uses - but the UMP is more compact than a 10.5 inch AR. That means that in close, cramped situations, its the superior tool.
The downside - its more expensive over all. Mags are a lot more expensive. Ammo is more expensive.
What is your intended use for the short AR? What is your intended use for the UMP? Are we talking in-home defensive use? Are you gonna become a post apocalyptic warlord / raider going house to house? Are you going to fend off angry biker mice from Mars?
I've got a 10.5 AR - it'll reach out and smack someone and make a hole a few hundred yards away. That UMP should do the same. Which bullet will have more energy on target, at distance? The 10mm will probably have worse ballistic arc at range, but its not really meant for long range engagements.
UMPs are cooler than ARs. Is this a toy? Does second kind of cool matter (there's a Nutnfancy reference for you)? Do you own an HK USP, P30, P45 or even a VP9 to accompany this gun and fulfill HK cosplay / roleplay fantasy? UMPs are not as cool as MP5's, but they're still cool.
You know you wanna to ze HK slap...
That's not saying much. I'd rather stick my dick in a hornet's nest than watch that pinko bastard.I will say this. I'd rather watch nutnfancy than the yankee marshal
He also wrongly accused Mrgunsngear of stolen valor. Yeah, **** that guy.I'll elaborate - fuckwit went up to the Chaz / Chop in Seattle and was on the side of the ANTIFags who were larping as revolutionaries. He was balls-deep in the BLM / Floyd protest shit with them. **** that guy.
Not only that, YM is an idiot!If you're not stuck on 5.56, 300 BLK is also a great option for short ARs. Even out of an 8" barrel, it's still a very potent round. 110gr at 2,100 FPS. That's more energy than a 5.56 will have out of a 12-13" barrel.
That's not saying much. I'd rather stick my dick in a hornet's nest than watch that pinko bastard.
He also wrongly accused Mrgunsngear of stolen valor. Yeah, **** that guy.