So I built an AR Pistol with a 7.5 in barrel. I must say there is nothing more fun but I have heard it called a "joke of a gun" and a "glorified .22" So help me to understand just what kind of stopping power do I really have. If there was a scenario were you had to hike through Grizzly country and you could have an AR with a 7.5 in barrel, a 5 round hunting mag and I will give you a sixth round in the chamber so you are carrying 6 rounds or you could have a Ruger Super Blackhawk .44mag with a 7.5 inch barrel and 6 rounds in the cylinder, which would you choose and why. I know we are talking about a slow heavy bullet vs a fast sleek bullet, but which would stop a charging Grizzly ?

Well, Lt Calahan said that the 44 Mag would clean take the head off, so clearly the 44 Mag with it's 240gr JHP, as compared to the 55gr FMJ.  But now if you put a piston on your pistol, it might be a different story.  We only talk pistons in this sub-forum.

Oh sorry! I did not have my glasses on....I thought I was in AR Pistols  *BLUSH*

Pistol, piston...close enough

Honestly you give up so much velocity with a 7.5" barrel that it really is just a glorified and very noisy 22 unless you're at super close distances...measured in feet, not yards. If you wouldn't hunt a bear with a .223 with a 20" barrel at 50-100 yards...there's zero chance that a 7.5 is gonna be useful in that case as anything other than a flashbang device, really.  Piston driven or not.

It's a fun toy noisemaker, that's about it. It does fill the "better than a rock or sharp stick" criteria but it's really not worth it. If you really want to do a barrel that short, look at 300blk supers instead. With a piston.

Hey I like my OA-93 - oops wrong forum and yep - just a noise maker ....

Ballistics by the inch.

http://www.ballisticsbytheinch.com/223rifle.html

Thanks for that link. Why did the tester choose those lighter grain bullets, specifically 45 grain?  Why didn’t he test 62 grain as well?  Interesting none the less.

I don't know for certain, but I assume they tested loads typically used in varmint hunting.

That chart seems to show muzzle velocity over 2000 fps for the 8" barrel.  How many .22 rimfires do that?  And with a 55 grain bullet.

Some people will always complain that a 2&3/4" .357 magnum with a 125 grain hollow points are a waste.  Poor velocity, lots of flash and bang.  They'll tell you a 4" is better.  Then someone else will tell them a 6" is the best.

Maybe the guy used the lighter varmint bullets for a couple reasons.  First, they're faster than heavier bullets.  Second, they would expand better than the heavier bullets at the lower velocities,  that's what they are made to do.  The varmint bullets usually just explode at higher velocities (rifle velocities).  I've seen some terrible holes in ground hogs/crows from 45 grain bullets out of a 24" M700 VS out to 200 yds. or so.

You didn't build it to do what a carbine or rifle is meant to do.  Did you?

Shoot it.  Enjoy it.  If you decide, later, it isn't what you really wanted the barrels are easy to change.

I've got an F250.  Will it tow as much as an F350?  Hell no.  But I didn't buy it to tow trailers.  So it will do what I bought it to do.  So I'm happy with it.

Sorry but the glorified .22 comments or myths are ignorant. If u can read u can see even according to ballisitcsbytheinch an 8" .223 is around 2500fps...almost well over 1000fps faster than a .22 in a 16" barrel...
So me..I'll take 30rds in .223 8" AR over almost anything.
What should be taken into account also is what do u shoot/train with more and can shoot more accurately and faster...
If a bear were charging you on all 4 legs I'm confident I'd put more rounds into its head area faster than trying to aim a 7" pistol in .44 and aiming at its head area.
Single action pistol? Having to cock it? Double action pull weight..?
My ar is gonna have a red dot so I have that helping also.
All this said I'm not bear hunting..if I were I'd probably choose some lever action bigger caliber I suppose.

Has anyone actually worked out the penetration on a 7.5" AR? When it comes to grizzlies specifically, everyone says penetration is kind of the name of the game. so for sure the .44 takes the cake.

Some quick math taken off ballistics by the inch:

.223 - 7" barrel - 55 gr
2190fps
586 ft lbs of energy
.1579 sectional density

.44 - 6" - 200 gr
1200fps
639 ft lbs of energy
.1475 sectional density

I don't really see how a short 223 is going to have more penetration than a 44, but sectional density isn't a great comparison anyways.

remember that for hydrostatic shock to take place, you've got to be closer to 2400fps(somewhat debated number) so neither round is getting there.

Back to the bear thing, like the other guy said. You'd never take a short 223 hunting bear, but people do take .44's on occasion and they seem to work out relatively well in hunting and self defense against grizz so there is a fair bit of data to support them.

I hope you are shooting suppressed...I have been next to an 8" AR and SOB, it was brutal....I cant imagine lighting off a few rounds right after another

This right here!

That was me about a month ago shooting a long rifle and some dude and his girl plops down on the bench to my left. The distance is maybe like 10-12 feet apart. All I remember is a concussive shock-wave slamming into my face and neck with a flash intensity that could rival del Sol…!!! The sound made my ears sing and teeth chattered a string of syllables starting with “ sweet mother Mary, what the hell was that”?

Unless you plan to scare the crap out of the bear, I’d be very comfortable with that 44 mag. A 460 or 500 would be better…..!!!

A friend has a large property in south eastern Ohio. A couple times a year we take our metal detectors and try to find treasures on the long gone homesteads there. No grizzlys but plenty of black bear so I carry a 5.5" Super Blackhawk in .44 and my friend has a Glock in 10mm. Neither of us carries a long gun because of the detectors and related stuff, water and a few snacks (we've learned to leave the beers at his house).
Anyways, a short barrelled .223 AR will kill a bear at close range but a Blackhawk is much easier (for me) to carry and deploy quickly from a belt holster. If I were just hiking through bear country a rifle in .223 would be enough but making noise while walking is better as the bears will tend to go away from noises they don't know.