223/5.56 16" suppressed bolt gun, 69-77 gr bullets.

Varget
8208xbr
Rl-15
TAC


If you can’t get single digit std. dev with those powders, there’s something else going on with your process.

Yup. I’ll add most of the Hodgdon Extreme series powders should make single digit S-D available. This can include H4895.

Ditto on H4955.

I’m a big fan of h4895 in my 24-26” barrels and 75-80eld’s, but it might be a bit slow for a 16”. If you can find it, it’s another great powder, but it’s pretty hard to find currently.

There is no “best.”  There is what “works well with your barrel” and the bullet, case and primer that you are using.

A semi-automatic AR-15 is not going to produce the same statistics as a custom bolt-gun due to the extra hole bleeding off gas in the semi-automatic AR-15 barrel.  Also, you need to use a minimum of a 10-shot string over the chronograph to obtain any significant data.

VihtaVuori N140 has produced repeatable single-digit standard deviations from my barrels using 75-77 grain bullets from Hornady, Nosler and Sierra.




….

Impressive. Never used Viht but have heard superb things about it. Prior poster did a good callout of matching burn rate against barrel length to get performance and consistency. I spoke just a bit too vaguely.

As with all things measured, bigger sample size lends significance. 5 shot groups and 10 shot strings are valuable.

I think best powder is secondary to internal ballistics and barrel harmonics. I'm a firm believer in velocity nodes and no matter what powder you use, if you can hit the velocity that is a node for your barrel, powder is secondary.