Ha, I am trying to fill the niche that I bought a 5.56 AR at an auction and luckily after the firing pin didnt fire, I had my son take it apart and we found out it was a 300 blackout stamped on the barrel under the rail......I thought about taking it back to the auction but believe it was an honest mistake that I can live with. So, now just trying to use it to harvest deer. We dont need it as we already have .243s, 30-30, and 3006s for deer but figured I would use it to its best potential. Will I be packing it during prime rut and hoping to harvest a decent buck - likely not. But, early and late doe seasons - definitely could be fun in the woods.

then I would pick up a couple boxes of the Winchester Deer season XP it uses what they call and extreme point

a plastic ballistic tip that sheds on entry and it basically has a big hollow point under the plastic tip box velocity is 1900fps muzzle and should be 1717fps at 100 yards by the box

I am hoping to go get some chrono data on mine next week.

a good way to think about 300 black out is from a 16 inch barrel at least in 150gr it is at whatever distance your at the approximately the same as 30-30 50 yards further out

so if you shoot 150 yards with a 30-30 that is the same weight and velocity you get at 100 yards with 300blk 150gr

AR's can get a little confusing that way if it started life as a 5.56 rifle and then found an new upper along the way the receiver may say 5.56 and the barrel 300blk

I would argue all recivers should say MULTI-CAL but they may not all say that.

what is important was you didn't go the other way thinking it was 300blk and it happened to be a 5.56 barrel

because 5.56 will chamber a 110gr 300blk but it is destructive to the gun when you fire it ,
not uncommon to blow the bottom of the mag out and bulge and break some stuff you could get hurt by flying parts
notice he was using 110gr vmax in the gun he blew up in the video

I assembled a black out to meet our deer cal restrictions on public land for my youngest son when he was 7. It was low recoil, adjustable, and when braced pistol were not sbrs the 8.5" barrel witn supressor was nice and short lowered recoil yet and still quiet enough with supper sonic ammo. Funny thing he shot his first deer with suppressed 7mm-08 and that evening his brother shot 2 with the Blackout just to try it out.

When I needed to make it an sbr since I'm not tec savvy I did try for the free tax stamp instead I just got rid of the brace since I don't have a need for the gun anymore. It works and we killed every deer shot with it I think between 5 and 10 but it's a limited week round and there are better options out for our needs now.

You have it may as well put it to use just know it's limitations.

Green County 180s out of a 308 are slow and kind of a turd. 150s I found do much more damage and always exit. If I were hunting elk I would use 180s in a 30/60 or one of the mags but can't see the benefits in a 308 for whitetail. My cousin was always shooting heave bullets in his 308 and not overly impressed. He finally started shooting 150 after me telling him to try them for a few years and he is much happier. More damage and deer drop or only make it 20 yards or so. Do you have big 250lb northern deer? Ours are135 or so for average down a big one would be maybe 150. Small yearling 70 to 100. Bigger deer may make a difference?

Honestly I prefer a 7mm-08 with 139gr or 243 with 100gr over the 06 I used to shoot preformance wise and fhe 06 should average 200 fps faster than the 308. I like my 270 better also than my 06 also. I never have understood the draw to the 308 for deer or 30 cals for that matter. Maybe in the 300 prc but then 338 lapua is better yet. .

We do have some nicer large framed bucks. My kids generally use our .243s with 100 grain corelokts or powershoks. We have harvested quite a few deer with these and the recoil is very manageable and a comfort to shoot for my wife and kids. I generally pack a 30-06 shooting 150-165 grainers and never lost a deer yet. I too prefer the .243 for comfort though.
Back to the 300 blackout - anyone try the tipped game kings from sierra - think they are the 125 grain? I like game kings but never tried the newer tipped game kings in anything. For that matter anyone try the tgk in any caliber? How does the bullet hold together? I generally like sierra and they are close to me

the 180s are a hand load of mine from the shorter of my 308 barrels clocked at an average 2625fps 21 feet from the muzzle
not exactly a turd
at 100 yards there is only a 120fps difference from the box velocity of the 150gr 308win deer season XP
I worked up it took a bunch of bullets and I found an accuracy node 1/2 gr under max load I found older books that put it 1gr under max
it works ,shows no pressure signs and I can neck size only the brass till the 5th reload then more because I choose to than because it gave me any issue I full length size.

they are the same speed as 150gr 308 Winchester deer season XP at 300 yards and carry more energy the entire time

I like 2 holes and I like a bullet that is still super sonic at a 1000 yards because I use the same bullets for target and game
I built that load with the goal of ringing steel at 1/2 mile and to go shoot with a friend that was shooting 1000 yards with 308win , he moved and so far I have only taken them to 1/4 mile but they look very promising at 1/4.

I have to confess I have shot more cows with it than deer but the deer shot didn't go any where either.

there is nothing wrong with 150s either and if I was only shooting deer with them I might just buy them off the shelf like that but I tried some 150gr factory loads and my gun just didn't like them very much, wasn't getting the accuracy I wanted.

the road kill I cut up Thursday was huge in the body and neck for a 7 point 3x4 probably right around 250