Originally Posted By: dan158
Lets say one shut off the gas system so bolt wont move for an AR.
One ejects cases manually by pulling the BCG back.. One has no swipe marks and brass looks fine.. But when gas system is running it leaves bad markings. Is it considered over pressure or just the timing at which can not be slowed down enough to function as a semi auto? There would be more time for the brass to cool down by manually eject with gas off than if being ripped out so fast before has a chance to cool and shrink.. Over pressure or not?? Then what would the signs be? The same as a bolt rifle then?? Thanks. Dan
I'm sorry but I have not done adequate testing to confidently answer your question, and I specialize in work with bolt action precision rifles.

My speculation would be that the gas system is part of the "expansion chamber" in a semi-auto, as is necessary for proper function in a gas-driven system. In order to read pressure signs effectively, the entire system must be functioning as designed. It is no surprise that bolt action rifles are considered to be much easier to work with, as this variable does not exist. There is no cyclic "timing" to worry about with bolt rifles. While I'm certain that the pressure shown in your hypothetical should be viewed as "real," I have not done adequate testing to tell you why it appears in semi-auto mode and not when the bolt is remaining locked. Perhaps someone with more experience with semi-auto's can comment.