I think I understand now
I've really never understood the diff between a mid length gas system and a full length gas system. They both are reliable and the only diff I thouyght was the length of the gas system. Today I went out and shot my Sig 556 Patrol SWAT and my SIg 551A1 at the same time. The 551 had a softer felt recoil. I would fire the Patrol three rounds and then the 551. Each time I felt that the 551 had less kick that the patrol. Is it me or is there a real diff between the two gas systems.
I expect there is a difference in recoil. Rifle length AR type rifles have softer felt recoil (to me anyway) than carbine length ones. I don't see why the difference wouldn't translate. I had a 556 Classic (longer gas system) and it was very soft shooting. I have a 556 Patrol on layaway, but I haven't ever fired one, so I can't compare the two as of yet. The trade off is that the shorter gas system is less front heavy, just like with AR rifles the carbine is lighter and shorter than the rifle.
A shorter gas system will have more recoil energy. The further the bullet travels down the barrel, the less pressure there is behind it. A shorter gas system means the gas is entering the tube sooner, at higher pressure. I would expect this also means a slight drop in muzzle energy and velocity.
You will enjoy the Patrol rifle. I really like mine and it handels well. I also have a Classic SWAT and it's a bit heavy up front.
You also have less mass / weight overall to the gun to deaden the felt recoil. Plus the patrol model loses that weight up front and may feel slightly more jumpy at the muzzle. Those both may be a factor also.