In answer to #1

The comp for lead projectiles blocks off the top ports so that your front sight does not get dirty from vaporized lead

You can actually shoot any projectiles through any comp

It just makes your cleanup easier


In regards to #2 and #4

iouri is spot on.

ALWAYS heavy crimp H110 loads and NEVER reduce H110 loads.


In regards to #3

In more then four decades of hand loading I have never found it necessary to trim a straight wall handgun casing


In regards to #5

All firearms are different. Learning whee that sweet spot is for YOUR revovler is part of he fun of being a hand loader


In regards to #6

I am not too sure I understand your question. Just Zero it at the distance you are shooting it.