I shoot bowling pins with a Rossi .357 revolver, which generally serves well in the role. I do, however, get complaints from anyone standing nearby that it spits a good deal of debris out the sides, and I've been hit in the thumb by bits big enough to draw blood, so I decided to have a look.
Cleaned the gun thoroughly after the last match, and had a look at the forcing cone. For you non-shooters, the part of the barrel on a revolver where the bullet leaves the cylinder and enters the barrel is generally cut with a bit of a funnel, the angle ranging from 6 to 18 degrees, depending on manufacturer.
Quality is usually pretty good, but sometimes a bad one gets out. I seemed to have gotten on of the bad ones as the "cone" was a 45 degree chamfer that extended only 2/3 of the way around the barrel, and looked like it had been cut with a rat tail file. Searching the web suggested that most pistol smiths leaned toward an 11 degree cone angle, and that coincidentally, Brownells stocked the cutter.
The cutter arrived in 4 days, and the job took all of 15 minutes. I now have an 11 degree cone that extends the entire 360 degrees of the barrel, and is to a uniform depth. Everyone says the cone depth is important, and over cutting will reduce muzzle velocity by up to 50 fps, which doesn't sound like much, but no one is willing to even estimate the depth limits. I quit at a modest depth that left a bit of the old chamfer showing at the top of the barrel.
I'm told that this operation will tighten up my groups and eliminate side splatter. Haven't been to the range yet. Film at 11.