I had a partial case head separation using a 1.8oz buffer

[DeNinny]

The projectile passing the gas port and uncorking from the muzzle are dramatically different. Gas port hardly provides any relative pressure relief to muzzle velocity as I mentioned before.

My analysis was simply comparing the effect of the gas port distances only. Had nothing to do with uncorking from the muzzle. To which I completely agree. It's absolutely going to be much higher whilst uncorking.

The reason is simple and I'll explain it differently than how I did before. Within the casing the gas from powder combustion is enclosed in a small volume. The case itself. The bullet is holding it all in until it uncorks. Once that uncorking occurs. The contained gas now can expand into the greater volume of the barrel and it will continue to expand down the barrel. All the while the pressure is dropping.

Then once it reaches the gas port it will clearly be at a lower pressure than at the mouth.

We have always been at 100% alignment here.

This isn’t me theorizing, but actual test results Bill A. did when developing Grendel, as well as numerous barrel length tests conducted by Rifle Shooter.

I asked him about it when we were discussing MLGS vs RLGS on 18” guns, the main question being whether 18” RLGS would have more velocity.

I appreciate all this real world insight. I would love to discuss the chemistry, physics, materials science, and metallurgy with Bill! You are lucky!

Gas port does bleed enough energy to get the carrier moving though. The closer the port is to the chamber, the more energy imparted into the carrier, which is controlled with port sizes. Smaller port sizes will choke the flow of gas back into the carrier to try to keep it relative to what a 20” RLGS will provide with its much larger port, but lower port pressure.

And all I was saying is that once the gas reaches the port, it now has two paths to go - continue down the barrel and return back to the gas key. And the second path back to the gas key is what makes the pressure drop because again the added volume of the gas tube itself. As such the gas pushing the bullet is slightly lower than it was if the gas port wasn't there.