Need help deciding on a caliber for 7.5-8.5 inch barrel

[brycewise]

I keep hemming and hawing over whether to go with 300 blk or 6.8 in a barrel of approx. 8 inches. I am not a reloadeder, and I don't intend on using a suppressor. My intended used would be unsuppressed, supersonic rounds for defense at 150 yds or less. I am primarily concerned with 25-75 yard performance. I would like to have the least concussive, lowest muzzle flash possible.

The dilemma I have is that I am not exactly blown away by the 300 blk performance. I like the higher velocity performance from the 6.8 with the lighter rounds.
Having said that, It seems like it is harder to find ammo for, more expensive when you do, and uses more unique parts then the 300 does.
I have ruled out the .277 wolverine. To me it doesn't seem like you get much velocity over the 300, its still a wildcat cartridge and I have doubts it will ever be widely produced. I would rather just use the 6.8, there isn't anything that the 277 does, that the 6.8 doesn't do better, and the 300 blk uses the same parts, so the conversion isn't any more or less convenient.

Anyways... help me decide. Probably the Ideal scenario would be if a ammo manufacture would release 90-95 grain 300 blk rounds getting about 2400 fps from a 8 inch barrel.
Anyone know if something like that is rumored to be in the pipeline?

[Auto-X Fil]

300 does much better, relatively speaking, from a short barrel, than those bigger cases. It is adequate for defensive use and offers substantially less blast. Use well-reviewed ammo and you'll be way ahead of a 9mm carbine, especially at longer ranges.

I am kind of assuming that you will practice a lot with this gun. For hunting, where shots fired at game tend to be a relatively high percentage of the gun's use, I'd always vote the higher caliber. Of course, those are normally longer barrels and used exclusively outside. Anyway, the extra rounds used at the range make the lower per-round cost of 300 BLK more attractive.

[LRRPF52]

You want 7.5-8.5" barrel, unsuppressed, supersonic, with "least concussive" and "lowest muzzle flash possible" all in the same shebang?

I know what this looks like in the end, and it is the exact opposite of the symptomatic characteristics you are trying to avoid.

Anything supersonic, from a 7.5"-8.5" barrel, is going to have insane concussion, and muzzle flash that is blinding at night, especially in a no-light situation.

You need a suppressor, pure and simple.

[brycewise]

You want 7.5-8.5" barrel, unsuppressed, supersonic, with "least concussive" and "lowest muzzle flash possible" all in the same shebang?

I know what this looks like in the end, and it is the exact opposite of the symptomatic characteristics you are trying to avoid.

Anything supersonic, from a 7.5"-8.5" barrel, is going to have inane concussion, and muzzle flash that is blinding at night, especially in a no-light situation.

You need a suppressor, pure and simple.

I would think that the more efficient powder burn would reduce the flash signature. Im not expecting it to be eliminated, just less if possible. If its not possible, then it is what it but if there is a difference between the two, then that is a factor that I would take into consideration.

I get the benefit of a suppressor, but in the event I should use this rifle in the role for which it intended (defensive) I would rather not have to try and explain to the Jury why I had a suppressor on my rifle. I will have a hard enough time explaining the reason I tagged someone with a rifle to begin with.

[LRRPF52]

Suppressor on your pistol or SBR?

Because you want to retain your hearing, and not end up like me.

[jstalford]

Anyways... help me decide. Probably the Ideal scenario would be if a ammo manufacture would release 90-95 grain 300 blk rounds getting about 2400 fps from a 8 inch barrel.

Lehigh has a 78 gr that would get close to that velocity, I believe.