6.5 grendel sbr powder. Choices

[LRRPF52]

Huge fireballs out the end of a barrel IS unburnt powder burning... Just an FYI.

Large flame from the muzzle is hot gas uncorking after being trapped behind the bullet. That gas is a result of the powder having already been converted almost entirely within the chamber. Once the bullet exits, the gas expands outwards behind it and produces a visible flash signature.

You would have impressive flames shooting out of the gas port vents in the bolt carrier if unburnt powder was present near the gas port, because of plug dwell.

Most of the assumptions about propellant conversion are not well understood by the layman, and there is a lot of gun counter myth propagation in this space by retail clerks with zero applied or theoretical physics backgrounds.

The peak pressure happens in the middle of the propellant column, which means that the acceleration’s primary impetus is from that state, from which it monotonically decreases as the projectile moves down the barrel.

The resultant energy being imparted on the projectile is the hot expanding gas wave that resulted from chemical potential energy being converted within the chamber.

You could find a powder/bullet combo that doesn’t convert well at all, and allows unburnt powder to evacuate from the barrel upon the bullet on-corking, but you will not see published data that does that normally.

This is one of the main reasons why powder and bullet manufacturers conduct testing of those combinations, to find optimum conversion in the chamber without exceeding peak pressure, but also not being too slow-burning.

[LRRPF52]

Published data works fine for 12” and 24” Grendels.

The powder is fully converted within the chamber + 1.5-3” ahead of it, especially with a short fat case like Grendel with a 30 degree shoulder.

The spark shoots into the powder column nicely with Grendel, unlike legacy cartridges such as .30-06, .270 Win, .280 Rem, .300 Win Mag, etc.

You’ll notice this dominant trend in the rifle cartridges developed over the past 2 decades, like WSM, WSSM, SAUM, 6.5 Creedmoor, 6.5 SAUM GAP 4S, 6.5 PRC, 300 Norma, etc.

For 12” Grendels, one hand load that works really nicely for target-shooting is the 107gr SMK on top of 8208 XBR.

I was just shooting factory 123gr ELD-M yesterday out to 800yds, working the steel from 200-on-out, and I was just hitting target after target like it was easy or something.

Hornady uses a canister powder for their factory Grendel ammo, so it’s hard to duplicate that load.

My buddy’s 12” Grendel I built for him using the same core components as mine really likes that 107gr SMK/8208 load, at 2450fps.

[Shooter31]

I kon some use mag primers. With these bullet combos and powders would magnums be beneficial?

[myrifle]

I kon some use mag primers. With these bullet combos and powders would magnums be beneficial?

Best thing to do is buy cci450's and only use them in your ar15 grendel(s)