Brownells sells a throating reamer in various calibers that taper the rifling just ahead of the chamber allowing lead bullets to swage into the rifling rather than the rifling cutting into the bullet and leading the bore. Just as with rifles that are throated to allow a certain AOL to be used. Pistols can greatly benefit from this throating when using a consistent diet of lead. It does not affect accuracy in any way. Talk to the technicians at Brownells. They are very knowledgeable about all matters relating to firearms.