Barrel for an Older M&P and other issues

[Gazz]

I have an older M&P sn 348xxx that was rebarreled at some point with a later barrel. The later barrel used has the thicker front sight and my frame has the narrow groove so I can't really get much of sight picture. Anybody have an older barrels with narrow (thin) front sight blade with nickel plate? Or should I just thin down the front sight blade that I have now? I do hate to modify old stuff though.

Also, when cocking the revolver single action, the cylinder does not always index properly and I need to give a little nudge to get it into proper position. I am thinking I need to put in a thicker hand, correct?