Is an adjustable gas block even needed?

[montana]

Question: How do you know when a rifle is so overgassed that it "won't cycle". vs. a little too undergassed to cycle? What's the specific behavior difference?

My 18" AA rifle was so over gassed that the casing would not even eject. The speed of my bolt carrier was so severe that the casing would end up jamming my action or lay right next to the ejection port. The bolt carrier speed was so fast, the magazine spring would not push the next cartridge up fast enough for the bolt carrier to catch the next round. This sounds like the same symptom as being under gassed, but the recoil and velocity of the cycling action is quite severe unlike under gassed which is quite lethargic. I had never experienced this before with any of my other AR rifles before, but I suspected it was over gassed. I had a screwed on front sight post-gas block and installed it on my rifle farther forward, "covering half of my gas port" knowing it would cut the port pressure. The action cycled, so I new it was way over gassed. I have shot factory AR rifles with the same gas tube lengths, buffer weights and noticed some manufacturers rifles were significantly softer shooting. The difference was the gas port sizes. The AK is legendary for reliable functioning with varied ammuntion types but it's recoil is quite severe since it is purposely over gassed. There is an adjustable gas piston for the AK https://www.youtube.com/watch?v=dFRaEe8nfxU that works similar to the AR adjustable gas block. Some gas blocks bleed the gas as others restrict the gas. I'll let others argue the virtues of which is better.