RE: Rossi .53
Yes, just raise the top of the port. I don't worry about any loss of compression, you'll have to run a pipe, anyway, and that'll make up for it. I don't mess with the transfer ports. I use a Dremel cut-off wheel to get thru the chrome, and a tungsten carbide rotary cutter to take out the brass. Smooth it up with a file ot the cut-off wheel. The plating won't peel if you work on a true ABC engine, I wouldn't recommend trying it on an ABN.