S&W 686P Cylinder Dimensions

[PaulTX]

I recently acquired a S&W 686P with a 2.5" barrel. I also have a Ruger Blackhawk. I just relalized the 686's chambers are smaller than the Ruger by around .001 to .002. I can drop a jacketed bullet right through the Ruger cylinder but they stick firmly in the 686. This concerns me because I also shoot hard cast lead that are .001 larger than jacketed.

Is there a reason for the 686's chambers to be smaller - should they be bored out?

Thanks,
Paul