Yes, flaring out the rough edges of the breach is a great idea. I did it to my NPSS, but I also purchased the Beeman pellet seating tool. Instead of using the conical end to push the pellet too far into the breach, I used the ball end to seat the pellet just beyond the breach face. As for flaring, what I used was the small conical sanding tip that is available for the Dremel. Use just your fingers and slowly and carefully turning the tip against the breach edges, making sure the flaring is even all around. Make sure you shove a cleaning pellet with a few drop of pellet gun oil, about 1/2" down into the breach so metal filings don't fall into the barrel. Then when you're done, take a rod from the muzzle end and slowly push the cleaning pellet back out the breach. The oily cleaning pellet should trap any metal filings as it comes back out. You don't have to do too much flaring of the breach; you'd be surprised how much of a difference 2/1000" makes.