6.5 Grendel barrel Length?????

[LRRPF52]

Powder conversion with most of the propellants we use in 6.5 Grendel is almost 100% complete within the first 1.5-3" usually, depending on the propellant/projectile combo.

"Unburnt" gets confused with "mostly-converted" powder that has already been burned and released its potential energy within the first few inches of the chamber, but leaves tiny residual particulates that are still very hot. We also get soot residue inside the spent case, which reloaders are generally familiar with.

If considerable unburnt powder was making it to the gas port, imagine what would be happening in your gas system.

Pressure and heat are greatest at peak chamber pressure, which is when the projectile has barely moved. Some adhere to the static projectile argument with it retained by the neck still, while the Army Research Lab shows primer-induced projectile jump into the lands, but still in contact with the neck.

Either way, those places are where the powder conversion happens. The potential chemical energy of the propellant compound is converted into an energetic gas wave when the primer detonates and ignites it, which continues to propagate for tiny fractions of a second after powder conversion. This is why barrel length adds velocity relative to the time the wave dwells in the bore up until a point where it doesn't, which is dependent on propellant volume, bore volume, propellant burn rate, projectile weight, and other factors. Even in the case of long barrels or insufficient propellant, the inertia imparted to the bullet is enough to get it to exit, with the rare cases of squibs where only the primer or unusually low propellant volume was detonated, leaving the projectile in the barrel.

This is why we have tested load data for specific rifle cartridges and projectile weights, because some powders don't convert well at all for the bore volume and projectile weight, and some convert too fast to the point of exceeding peak pressure set by SAAMI. For example, you wouldn't use really slow-burning propellants in 6.5 Grendel, like the kinds we use in large case volume magnums with larger bores.

The flash you see at the muzzle is the result of the converted gas wave once it hits open atmosphere with more oxygen present to feed the exiting hot gas, not unburnt powder continuing the conversion process. You will often have small particulate matter exiting the muzzle left over from the process, as well as jacket material from the bullet. At night, you will normally see sparks along with muzzle flash from a lot of guns. The residual particulate matter from the propellant is still extremely hot, so when you do see fiery little specs from short barrels at night, that's what you are witnessing.

To have unburnt powder flowing into your gas system would be really bad.

I would also point out that if you're on a phone, it may create the typo, "handy capping" when someone is trying to say, "handicap".

Of course, "handy capping" could be a serendipitous happy accident that gains traction as a convenient way of executing suckahs in the ghetto with a G-Lock fo-tay.