I am looking at getting a 30 cal can in the very near future as well as doing an sbr. I am aware that the wait time on the stamp is pushing a year.

Anyway, I also plan to start a new AR build in 300 BO but have very little knowledge of that caliber.

What is the best length and why? 9.5-10.5 or 12.5? I plan to shoot mostly subs but some supers as well. I want good accuracy terminal ballistics out to about 150yds.

What twist and why? 1-7 or 1-8

Also what is a quality brand?

Thanks

Im probably in the minority here but IMHO 300blk is overrated. I jumped on the 300blk bandwagon a couple yrs ago and didnt take me long to get off. If I want 30 cal I grab my 308 or 7.62x39.

My opinion mirrors jeepercreeper's. I believe that the 300 blk exists because folks have all these AR's and have finally realized the limitations of the 223. Now they want the same gun and a better cartridge. Unfortunately, that small cartridge case just isn't going to allow much of a serious cartridge. I just can't see spending a bunch of money for an anemic cartridge.

My opinion is likely to irritate some folks, and that isn't my intention. But...that is my opinion.

I partially agree with the above but it filled a gap in my arsenal. I hunt mostly short range (100 yds max) and the 5.56 was not doing it for me. Had AR parts sitting around and was only the cost of a barrel away from the build.

If the 5.56 isn't doing it try a 6.8. I flat love my RRA 6.8 which has dumped some pretty good sized hogs 150-200 yards.

X2

This. At a dollar a round its a one big gimmick, you can build a 308 AR thats nearly as lite (I have built 3 now that weigh 8 pounds) and will smoke it everyday of the week and twice on sunday. At 50 cents a round.

If ammo was cheap it would be a viable option, but at 1 dollar a round and AK performance its meh at best.

A 6.8 in 11ish barrel is where its at 95 grain TSX going 2600 fps is bad medicine.

300 blk out is the main round I shoot these days. I guess you could say I have a man crush for the caliber. I've gone from shooting large 300 WIn Mag and 270 Win rounds, to wanting something more compact. When shooting supersonic ammo, the 300 blk out has about 1000-1100 ft lbs of energy, which is enough to take any Texas animals. The deer and pigs I have taken with it, all have been DRT shots, except one large boar that went about 40 yards. I shoot all supers for hunting.

The subs are a different animal. You have a 200 to 245 grain bullet doing around 1000-1050 fps. These rounds (with typical bullets) will not expand on game. And, they lack the "shock" of a supersonic round. It is like shooting an animal with an arrow with a field point on it. You generally get a .308" hole going in and a .308" hole going out. It's basically like shooting a 45 ACP in a rifle platform with no expanding bullets.

If you shoot the supersonic ammo, it is a very effective round.

My primary rifle is in 6.8.

I was just looking for a fun and quiet round but if the subs are near useless for hunting I may just put the can on my 6.8 and enjoy the quiet fun with a suppressed sub 22lr pistol and rifle

this! i think many people were expecting more out of the sub ammo for stopping/killing power but just not going to get it with any sub ammo bec the bullet isn’t expanding. All about shot placement tho. Next year this will be the only rifle I take to the stand bec I have had nothing but good luck with mine and most shoots will be within 200 yards. also if you dont like it just change out the barrel back to 556 and your not out that much money.

It's over rated in a sense because too many people try to make it into something it's not. It was designed as a quiet subsonic round that used readily available 308 bullets and was easier to load with standard powders verses trying to download the 308 cartridge. When used with in those parameters it's a great cartridge for what it designed to do (as the 300 Whisper) in a fast twist barrel. AAC over hyped it by comparing it to the 223 and 7.62x39 when really its in a stand alone specialized category of subsonic rounds.

I just don't get it but more power to you

I've owned a few ar pistols , a Daniel defense rifle , and a Remington bolt gun in the caliber . They are cool to have to say hey listen to how quiet this is , that's about it . Subs are fun but useless . I remember shooting em at 400 yards and the drop with 50 yard zero was around 240 inches . I no longer own a 300 blk

My first experience shooting 300blk was when i tried sighting in at 100yds with subsonic ammo. Boresighted rifle at 100, no bueno, move to 50yds, no bueno, move to 25yds, oh now i see holes. Never experienced being that far off when sighting a rifle in. Sold my 300blk upper and ammo a few months later. Just seemed pointless.

Very true. But I love how quiet it is!

another question

Why do so many use a pistol gas tube and some carbine? Is the pistol length better for subs due to less gas flow?

Thats my guess, I have seen a lot of pistol length gas holes on 16" barrels lately.

I believe pistol length gives it more gas ...

Subs are not useless. They are perfect for pest/varmint killing when being quiet is of great importance (ex: close by neighbors or shooting coyotes, coons, etc.. from a deer stand). I like a 308 (suppressed) personally because I can swap from hunting loads to sub sonic while in the stand, and not spook every deer in the county.

Ok u can have a few good uses for them . I guess 50-75 yards to feeder doing pest control would be perfect , I just never did much of it . It was fun hitting the gong at 400 yards with subs though! Took forever for bullet to get there

They make sub bullets that expand now. Outlaw state and Lehigh defense have them. I use mine to night hunt hogs and such. The Lehigh ME 194 sub hurts em. Its a 100 yd weapon though for me. I can group the lehigh subs to about an inch or so at 100 of the lead sled. If going out to more than 100 I grab anyone of my .308s. I wouldnt trade it. The Hornday 300 whisper 208 amax is accurate in mine as well. Better have good shot placement with those and was atated above, you will get a pass through. Good for what it is, but not a medium/long range option. And dang is it quiet sub/supressed.

The pistol length gas system has the gas port closer to the chamber, which allows for MORE gas flow. The pistol length system will generally cycle the subs better, since it allows more pressure to the bolt.

I did same thing as jeepercreeper....was simply in love with it.
It shot every bullet weight accurately.
Then I started hunting with it.
The first few small pigs went well.
Then I started shooting big pigs and got tired of watching them run off.

Switched to 6.8x43 and started dropping pigs.

It's not the 300BO'S fault, it wasn't designed to shoot pigs.
In a suppressed, close range envoronment hunting thin skinned things, it works well.
Shooting pigs with one can be frustrating and fruitless!

I know you can kill pigs with a .17 but I'm not play hunting and don't have time for that perfect shot everytime, I in feral pig control mode and want them dead when I shoot them.

Close....and partially correct
It's more about the timing.
The closer the gas port is to the chamber, the quicker and more violently the bolt starts to move.
On a pistol, accuracy is usually not the main concern, they just want it to cycle.
A 16" AR barrel chambered in 300BO, shot sub and suppressed would probably cycle with a pistol length gas system where as it might not with a carbine length.
On a longer barreled rifle, a rifle length gas tube opens the bolt much later after the hammer drops and more gently so you can stay on target better BEFORE the bolt opens and the bullet is out of the barrel or close to it.

The standard gas systems from shortest to longest:
Pistol length - quickest, most violent
Carbine length - slower than pistol - pretty much the standard in 223/5.56
Mid length - slower than carbine - sometimes used in ARs chambered with larger cartridges with more power to smooth them out.
Rifle length - Slowest, longest lock time, possibly most accurate and usually used on longer barrels

You can also alter the gas pressure by drilling out gas ports on barrels but that is a last ditch thing, really shouldn't be done without REALLY ruling out EVERYTHING else and could make the barrel require an adjustable gas block from that point on - JUST DON'T.