here is the el-cheap-o way to do it. I did this on a Smith and Wesson 25-2 in 45ACP. First I went and got my case mouth deburer tool and run it by hand over each cylinder, than that wasn't enough to suit me so I got one of those cheap cone shaped dremel rocks from a local auto parts store and chucked it up in a 1/4 inch drill and champfered each cylinder until I was happy with the results.It has been a long time but I believe I finished up with some emery cloth after that. Most gunsmith won't champfer the chambers as much as I like for liability reasons.I did mine pretty big.Probably at least 1/8 of a inch bevel.Do this at your own risk.you can use the moon clips with rounds in it for comparison. If you will notice the taper on a 45ACP case is quite a bit so the case is unsuported back there anyway for a ways in the cylinder.Use that for a gauge.I shot many heavy major loads in IPSC for several years with that gun and never had a problem.I always used 230grain lead roundnosed bullets and I could literally throw the shells in the cylinder from 6 inches away.I am not kidding!