RE: barrel length
No there is very little differance in velocity and none in accuracy.
No, I tried porting a barrel, very little differance in recoil [which is why it is usually done] it makes a lot more differance in high power smokeless guns because of the gas under several times more pressure when it escapes the port has a rocket push effect to reduce recoil. The real differance in having ports in a BP gun is that you have to clean them now thats a pain where th sun dont shine. Lee