Best AR Cast Cartridge?

What cartridge is the best to use with cast that AR uppers are commonly available for?
What sets it apart from other cartridges, makes it better?

I have a .300 BLK upper that I only shoot cast through. It does very well and is alot easier to cast for than .223 or 6x45.
.45 bushmaster is a pretty good cast slinger too.

Agreed. This is going to be a great cartridge with cast.

Rich

I have a lot of fun w/cast boolits in my 458 Socom. Like a semi auto 45-70.

hicard,

true, but that is a big mouth to feed.

Brass is horrendous, pricewise; boolits will deplete a pot in about eight minutes, and you need an ice cream scoop to load the powder.

By comparison, the 300 has cheap brass, lighter weight boolits, and does not need much powder.

And, it is a light recoiler.

Rich

So, I say: one of each!

He does have one of each!

Since I'm having a hard time with the 6x45, I'd go with something larger. Funny though, after handling the little bullets and cases, picking up a 30 caliber boolit, or an 06 case is like picking up an artillery round. If I had it to do over again, I'd have had 82nd Airborne make my upper using a 30 cal Wilson barrel that I have rather than the 6mm Obermeyer. I have lots of 30 cal molds, some that would suit the .300BLK.

The 300 fireball is fun to play with. I believe this is a 300 whisper with a different name. Supersonic with H110 & subsonic with AA1680 under 200 gr cast. Model1 sales upper.

Is the 300BLK the same as the whisper/fireball?

Uppers in pistol calibers are a riot & cheap to shoot w/cb's.

they all will shoot well if you have a good barrel with straight chamber and cast friendly throat and leade.the 308 is good also if you don't want a mouse gun.the quality of the rifle is more important than the calibur.the best luck I've had in easy to fing good cast boolit loads have been in 45 cal rifles.they do use more lead but performance on game is superior out to 2oo yards and accuracy is excellent also.if you like DRT or good blood trails the 45 is great,if you are just going to punch paper and plink the 300 BLK would probably be the way to go.I'm hoping to get a 450 BM from Aaron at Delta Company Arms and shoot some boolits that do very well in my 45 colts and 454 casull.I like working with straight wall cases like the 450 BM.

slight dimensional differences. The Whisper necks up the 221 FB case, which thins the necks quite a bit. That leads to split casenecks.
The BLK was developed around shortening the 223 case and not needing to neck it down very much. I believe it makes for a stronger case, more reloads, etc.
Besides, JD Jones is a d--k, and this waltzes right by him.
Subsonic, a 240gr SMK or 250gr NOE at 1050fps with a suppressor is going to be hard to take.
a 125-135gr J-boolet at 2200+fps will be plenty for deer-sized game.

Rich

What!
No .40 cals built on the 35Rem case?

But seriously, I'm a little surprised that nothing better has come along. Then again, maybe not because what is available in jackets will surely drive the market.

I'm really enjoying my .450B

As far as the .40s go they fall in between the diameter that will double stack in a basic AR mag, and the larger diameters that can single stack. It takes more than just a special follower, or tweaking the feed lips, to keep those in between diameters from all popping out the top of the mag.
BD