I'd really want to study up on ammo types and such. 300BLK is meant for short barrels like that, so that's why I was drawn to it for a small home-defense AR

I always imagined getting a 5.56 with like a 20" barrel and I don't want to swing that thing around inside

I had a 20" AR and I liked it, but not for home defense, true.

however I'd suggest that the AR-15 is actually a good home defense platform in 5.56

turns out dry wall doesn't do nice things to the 55gr round.

it does a lot of deflection because its low mass, high velocity.

they don't over penetrate as much as you'd think.

but 300 blk is a MUCH heavier and bigger round.

yeah, that's the fragmentation I spoke of. The 5.56 is actually pretty good for interiors because it breaks up when it hits something, but 300BLK won't and that's bad here

the main thing is train with what you shoot.

and 5.56 is cheaper to train with.

so buy two uppers, one in 5.56 and one in 300 blk

same pistol lower.

swap and pick.

I'd rather avoid having both. 300BLK will load into a 5.56 and then very bad things happen

its the other way around.

5.56 will load into 300 blk, but not vice versa.

300 blk into a 5.56 upper would cause you to have a jam because its necked differently.

but the case is shorter, so the bolt closes on the 300 and then your gun explodes

but 300 blk is a 5.56 cartridge so it will accept a 5.56 no problem.

I mean, clearly mixing ammos isn't nice.

so.... just dont?

5.56 with Frangible rounds are good for home defence. Get a pistol AR or a 16in with a 15in rail is a good idea for CQB.

my problem with 300 blk is that virtually no one actually has it.

300blk will not fit into a 5.56 bartel5

Barrell

Well order the rounds from Graf and Sons

Or lucky gunner

if I can't buy it at walmart, I don't want to expect to have it any time.

i wouldn't rely on it for home defense.

True

you might not be able to buy it and that would suck.

https://www.thefirearmblog.com/blog/2015/01/13/psa-always-known-caliber-300-blk-5-56-kaboom/

mistake 1: polymer lower.

mistake 2: being a moron.

300BLK doesn't exactly "chamber" in a 5.56 rifle, but there's enough room for the bolt to close

ahhh

that makes sense.

Yeah its going to feed but cause an explosion on the chamber as it

I'm guessing that its tight enough to force a round to push back into the brass

True