I just mic. three model 12's at pot shoot Sunday, all the bore's were .735-.736 and the muzzle was .696-.698. On one of the bbls. the choke stated 3 1/4" from the muzzle, the other two the choke stated 2 1/2" from the muzzle. BY THE WAY THE ONE THAT STATED 3 1/4" FROM THE MUZZLE SHOT THE TIGHTEST AND BEST PATTER. dOES THIS TELL US THE LONG CHOKE TUBES ARE BETTER. I DON"T KNOW.
Most of the older Model 12's with nickel-steel barrels had the longer choke section. I have one and it seems like it shoots a tighter pattern than the newer ones I have that don't have nickel-steel. The older one is great for handicap.