Here's an old trick: Make a gage to limit the bevel to just what you want, and keep it uniform for all chambers.
This gage allows adjusting the chamfer cutter with micrometer precision for uniform cuts on all chambers.
Get a block of hard wood.
Get a short, large bolt that has a shaft that will just fit into the chamber.
Cut the head off the bolt and flatten and true up the cut area.
Screw the bolt into a hole drilled into the wood block.
Put the cylinder over the bolt with it in one chamber.
Turn the bolt into the block until when you put the cutter pilot into the chamber, the cutter face just touches the edge of the chamber mouth.
Turn the bolt in until the cutter cuts a chamfer to the depth you want.
Then you simply put the next chamber over the bolt and cut until the cutter stops cutting.
All the chambers will have the same chamfer.
I made a more professional rig from an aluminum block with a lock nut on the bottom to lock the bolt at the correct depth.
You can also do the same thing with a drill press with a depth stop.
UNPLUG the press and unhook the drive belt.
Lock the cutter and pilot in the chuck and set the press depth stop.
Turn the chuck by hand to cut the chamber bevel, then cut the others.
