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

[LRRPF52]

All other things equal, I see this as entirely plausible (Edit: no comment on the damage part, though). To clarify, though, I see it as pressure drop off from the gas port distance as opposed to the barrel length. But I nitpick because it's basically the same thing.

The gas port is a point of depressurization. Prior to reaching it, there is higher pressure. Upon reaching it, pressure starts to drop more than if it would without a gas port.

So absolutely the sooner the bullet reaches the gas port, the sooner the pressure starts dropping. Shorter gas port, earlier pressure relief. (All other things equal.)

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.

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.

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.