So I was trying to imagine how a piston system would help prevent the problem of gas port erosion in a CAR length gas system, specifically the LMT piston system, which seems to have the gas block at about the same location. But because the gas hits the gas port before it encounters any part of the piston, it wouldn’t seem to make any difference to the actual erosion of the gas port in the barrel.
But the gas piston systems are self-regulating, correct? So while gas port erosion exists also in piston system, the excess gas produced is just vented out, and does not contribute to a speeding-up/stressing of the operating system.
Is that an accurate summary of the situation? Is the actual erosion of the gas port anything to worry about, or is it just the excess gas the erosion creates that is the problem?
i would imagine that the vent ports would have to be opened up to match the increase of gas flow from the enlarged port for all things to remain equal.
The shorter the gas system the more the gas port erosion. The softer the barrel steel will also have faster gas port erosion than harder barrels. Gas piston guns cycle much slower than direct impingment guns even though they typically have much bigger gas ports. Almost all piston guns require more gas to run than do direct impingment guns. So even if the gas ports get bigger overtime this won’t cause many problems. Piston guns may have less gas port erosion due to the fact that many start out with much bigger gas ports than direct impingment guns of the same barrel length and gas system size. I’ve seen many gas piston 16" carbine length guns which have gas ports in excess of .100"
in excess of .100" - that’s like over 40% of the internal barrel diameter! i always thought piston guns were supposed to be more efficient in their gas usage!
You thought wrong. Contrary to the nonsense floating around the Internet that gas-piston uppers possess some magical ability to propel a bullet “up to 200 fps faster" than a direct impingement upper with the same length barrel, due to them being “more efficient”, actual testing has proven this to be completely false. The following data was obtained using the exact same barrel as a direct impingement system, Ares piston system and a single shot system (gas port clamped off.)
molon, perhaps i should have said that i thought that as the gp systems were shorter in length, they used less gas than the di system (efficient not being the correct term). i do not consider that either systems have magical properties. thanks for the detailed chart.
