Is the shorter gas system on the patrol and pistol much harder on the action the way a carbine M4 is? In videos they look to shoot equally as smooth probably due to the fact that the gas system bleeds off the pressure once the piston gets half way back. I was just wondering because everyone says the Sig is so over gassed to begin with and I have had M4's rip rims off. Are the gas ports a different size on the pistol/patrol to compensate for the higher pressure closer to the chamber?
adam38654
Rifle length gas systems are almost "always" best. Especially with DI AR's! The 16' 556 rifle will be better than the 16' 556 patrol gas system pressure/wear wise. However the sig556 specifically the patrol/pistol/sbr's like the 556 rifle has a piston and gas regulator. That makes for less over gas problems like short AR's have. Still the patrol gas system was made for a 10.5 barrel not a 16'. I don't know for sure but I don't think sig uses a smaller gas port for patrols vs 10.5 pistols/sbrs. Some people love their 556 Patrols. Some say they are over gassed and have problems. Honestly unless I was going for a 10.5barrel I would not get the Patrol short gas system.
R
R
One thing to keep in mind, AR gas tubes and gas blocks are completely sealed as opposed to piston systems like the 556. This means that the force of all the bled gasses contact the gas key on an AR and it is easy to overgas.
The 556, on the other hand, has 2 bleeder vents on the gas block and 3 in the piston tube, so excess gas can exit the system. If you dont think it makes a difference, punch a small hole in an AR gas tube and have fun trying to get it to cycle. Also, if you look at the piston head on the 556, you will see a hole that goes through the bottom to the front end of the head. This is the hole that gas passes through and expands against the front of the gas key, so when the piston begins its rearward movement, the part of the piston head between the hole and the front of the piston shuts off further gas from entering the gas system (i.e. if you pull the piston back slightly, the gas port is shut off until the piston has passed completely over it).
Also, since the 556 has a fixed ejector, you would be able to determine if it was over gassed by looking to see which one shot brass farther because if it was overgassed, the bolt would travel faster and cause the casing to hit the ejector at a faster speed, sending it farther. Patrols and full length rifles eject brass about the same distance, so I really doubt that patrols are overgassed.
The 556, on the other hand, has 2 bleeder vents on the gas block and 3 in the piston tube, so excess gas can exit the system. If you dont think it makes a difference, punch a small hole in an AR gas tube and have fun trying to get it to cycle. Also, if you look at the piston head on the 556, you will see a hole that goes through the bottom to the front end of the head. This is the hole that gas passes through and expands against the front of the gas key, so when the piston begins its rearward movement, the part of the piston head between the hole and the front of the piston shuts off further gas from entering the gas system (i.e. if you pull the piston back slightly, the gas port is shut off until the piston has passed completely over it).
Also, since the 556 has a fixed ejector, you would be able to determine if it was over gassed by looking to see which one shot brass farther because if it was overgassed, the bolt would travel faster and cause the casing to hit the ejector at a faster speed, sending it farther. Patrols and full length rifles eject brass about the same distance, so I really doubt that patrols are overgassed.
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