Originally Posted By: Tempest
Originally Posted By: chevrofreak
Moving parts in a gas system is not a bad thing. If it keeps the receiver and bolt carrier cool and clean, it's a better design.
What part of a gun is going to stay cool under heavy burst fire? The barrel will get REALLY hot no matter what you do and the bolt/carrier are in DIRECT contact with it at all times other than recoil, and steel transfers heat really well...as does brass.
If the parts aren't getting to ~1000F for any length of time, you aren't affecting the metal. If you are, then you have to replace the barrel as well sense it will be subjected to the most heat...which is why belt feds have quick change barrels but not quick change bolts...
The barrel getting hot isn't really going to affect reliability. There are no moving parts in it that need lubricated.
I've seen FLIR video of an M4 being fired full-auto with a DI upper and a piston upper. The bolt carrier gets hot very quickly with the DI gas system, and the bolt carrier and action of the piston upper stays quite cool through the entire burst. It's a very dramatic difference.
Subjecting oils to that kind of heat breaks them down very, very quickly.
Originally Posted By: chevrofreak
Moving parts in a gas system is not a bad thing. If it keeps the receiver and bolt carrier cool and clean, it's a better design.
What part of a gun is going to stay cool under heavy burst fire? The barrel will get REALLY hot no matter what you do and the bolt/carrier are in DIRECT contact with it at all times other than recoil, and steel transfers heat really well...as does brass.
If the parts aren't getting to ~1000F for any length of time, you aren't affecting the metal. If you are, then you have to replace the barrel as well sense it will be subjected to the most heat...which is why belt feds have quick change barrels but not quick change bolts...
The barrel getting hot isn't really going to affect reliability. There are no moving parts in it that need lubricated.
I've seen FLIR video of an M4 being fired full-auto with a DI upper and a piston upper. The bolt carrier gets hot very quickly with the DI gas system, and the bolt carrier and action of the piston upper stays quite cool through the entire burst. It's a very dramatic difference.
Subjecting oils to that kind of heat breaks them down very, very quickly.