300 BLK vs 5.56mm for barrel length efficiency

[rcsaxby]

Yeah I used to really want a 14.5 inch AR until I started hearing how the round was designed to be shot out of a 20 inch barrel.

[rsilvers]

300 BLK is best with about a 200 yard zero for normal ammo, and a 100 yard zero for subsonic.

[blacklabel66]

Does anyone have a chart showing the drop using the 200yrd zero and supersonics from 0 to say 300-400?

[M4Fundi]

Scrap all this. I am redoing it with a different method.

Looking forward to this

I just bought a Ti-Rant 9, Ti-Rant 45, M4-2000 a couple of weeks ago and I would buy a 762 suppressor and a 300BLK upper tomorrow if I could get a little more educated on the cartridge exterior ballistics.

If I was 25yr old I would be out getting an AAC Tattoo
No ink for me I think I'll spend my $ on guns, gear and ammo

[fixit69]

As if we're not asking enough... suppresed graphs with barrel length and trajectory, etc, etc, blah, blah...

Seriously, any info would be much appreciated, especially suppresed.

Thanks for the work you've done and the work you will do in the future.

[M4Fundi]

Mr.Silvers any news on your testing?

[Pappabear]

Silvers,

let me give you an easy one. I scrapped my 6.8 SBR. But I am still interested in an SPR build for a 6.8. What would be the ideal length and where is the point of diminishing returns with regard to barrel length on this cartridge. Or is a 6.8 SPR just a bad idea?

Thank you

PB

[rsilvers]

With 300 BLK you get 8 inches of barrel for free compared to 5.56mm, so I would do a 300 BLK SPR as a 16 inch. For 6.8 and barrel efficiency, it would have about the same rate of diminishing returns as a 20 inch.

[Pappabear]

To be clear, you would do a 20 inch 6.8 SPR?
Thank you for your reply.
PB

[krm375]

What would the 300 BLk vs 5.56 trajectory chart look like with a 16 inch barrel.