300 BLK barrel length compared to 6.8 and 5.56mm

[angusbangus]

Is there anyway you could make that spreadsheet available? Or send it via email? If so, I'd like a copy.

[Z71]

Is there anyway you could make that spreadsheet available? Or send it via email? If so, I'd like a copy.

I am bumping this thread back to the top because the original data is not available. I'm in Texas so I don't think the problem is my country of origin!

[dellet]

Couldn't find the original source, here's a copy.

http://www.silverdoctors.com/wp-content ... 208801.png

There is another that is 300/556 in here.

http://www.300blackoutarrifle.com/uploa ... 00-blk.pdf

I think I have printed versions at home that I could scan and post.

[A-Game]

300aacblackout.com has been up and down over the years.
I don't know if it is owned by Robert or AAC but I would be surprised if it doesn't come back up.

[Z71]

Couldn't find the original source, here's a copy.

http://www.silverdoctors.com/wp-content ... 208801.png

There is another that is 300/556 in here.

http://www.300blackoutarrifle.com/uploa ... 00-blk.pdf

I think I have printed versions at home that I could scan and post.

Thank you!

[GSO]

Thanks to Dellet for saving everything!

I did a bit of poking around with Google and could not find any barrel length data for other loads. I'd be particularly interested in how flat the graph is for subsonic 300BLK. My guess is "very," but I'd like to corroborate that with some actual data.

[threehundred]

Shorter barrels are stiffer for the same diameter.
Could also be a harmonic effect.

-Lee

This ^ , I have cut barrels many times and achieve tighter groups everytime.

[threehundred]

I'm getting much better accuracy out of 150gr bullets than many folks are seeing out of 125's. Length of bullet has a factor there - the longer (heavier) bullet has less distance to jump into the lands. It's also possible that the harmonics are such that a heavier/slower bullet is a better match for consistency. Then you get into over rotation, and things get even worse for the little speed demons.

Accuracy is the product of consistency. The barrel is going to "wiggle" as the pressure and shock wave travel through it. Pushing a load to just short of case failure is not likely to be the most consistent (often, it's detrimental to accuracy). If you need ultimate ft/lbs for hunting ethics, you might have to give up some accuracy.

The 300BLK's throat is a compromise for being able to eat big heavy bullets for subsonics, and still being able to run the lighter supers. It's not a tight benchrest chamber. Accuracy will take more trial and error than a less versatile cartridge which operates in a smaller window. There's no free lunch.

I agree, in fact, I came to similar conclusions about 300BLK after a coupe of years dealing with its unique reloading characteristics, imo. After hundreds of loadings that failed to satisfy my OCD requirements, with only a few great loadings, I came to a personal conclusion, the 300 BLK does everything I ever wanted in the 1,000 FPS to 1,300 FPS parameters with 200 plus weight bullets.
Which fulfills my many decade aspiration for a profoundly efficient, dependable and impressive, pistol caliber in an AR pistol. Yes, I call the 300BLK subsonic load, and, just over subsonic velocities, a PISTOL CALIBER.

https://www.youtube.com/watch?v=Ely6T4ZfSls This vid is why I finally, and happily, gave up on building a 45acp SBR.

I have completely given up on supersonic loadings for the 300BLK cartridge, no mater what barrel length, because I have come to the conclusion it just isn't worth the research and development to get it to peak performance, at my level of expertise. I am sure many here have, and are quit happy with what they have accomplished.

But, If I want to hit something consistently past 100 yds, I have both a 223rem and a 308win for that job. In fact, I carry my 233 upper in a shotgun shoulder scabbard when I go to my range. Changing out uppers is more satisfying for me than carrying two complete weapons. So, the most efficient length barrel doesn't enter into my reality, as much as a short, fat, stiff, accurate barrel does.

Bottom line, I wholeheartedly agree with the OP, concerning his opinion that a 16 inch barrel is all that most shooters will ever need. I have a 10.5 300BLK because, as in the linked video above, it does all I want from it.

I guess, in my later years, I am slowly realizing that not ever weapon platform, can do everything I want it to do.

Good post, interesting thread read, thanks!