Phatinjun,
That is interesting load data from the factory. Do you know the velocities that go with these loads?
I think I am going to cut my .58 to 20 inches also. Have to cut a new dovetail for the front sight and re-attach the ramrod sleeve afterwards, but I think losing eight inches would really help in the field. Hell, I just might use the eight inch cut off piece and make a pistol out of it!
I picked up a .25 acp breech block to try but it must be for the later guns as it's allmost .250" short. So since I have to make a new plug to fit my 1973 rifle, I just may make it to take the .45 acp instead of the .25. We'll see.
Cat