The 65-3 was replaced due to 'reduced torque rifling' - RTR. The spin of the bullet in normal rifling causes a certain amount of torque in that direction, and the eggheads thought they could fix this (minor) problem.
So what do they do? Create opposing rifling indentions.
To simplify this, it's fixing your car's tendency to veer left by bending out the right wheel.
The -1, -2, and -3s were all failures. -1 had the RTR, but an idiot had mangled the twist rate between the two. The bullets wanted to keyhole while still in the barrel. The -2 was done better. Here, the rifling just shreds the bullet jacket and spits it out smoothbore style.
Then came the geniuses to the rescue. They decided that the RTR wouldn't work when done simultaneously. What to do? Right-turn rifling for the first two inches, left-turn rifling for the last two.
Still tore jackets apart, but this time, it gave you a nasty, twisting recoil vector. The 3" models just had that last inch of left-hand rifling chopped off. Accuracy's about equal to the -1 with a 90gr bullet, which is to say, poor to decent. There's a reason the FBI went to semis after issuing the 65 in some quantity. Leading is a major issue in -1, -2, -3, as you can guess. Beware!