Yes, here is the skinny. The forward cut is in line with the cyl. face. It's shallow at the very top and gains depth as it progresses down the side. This mimics the fouling cut that the Colt arbor (originals) have and allows fouling to bypass the intersection of cylinder and pin/arbor. The helical cuts alow any fouling that doesn't "bypass" to migrate to the rear as the cylinder indexes through repeated cycles. Those cuts are also through what will be the forward bearing area for the cylinder so be careful.
To make the reduced area of the base pin, I make another cut about 1/8 - 1/4" behind the front one. Using that as a mark, I reduce the dia. of the pin using a drill motor and a 1" belt sander (redneck lathe), and stopping at the end of the flat that D.J. posted about. That flat is there to allow the pin to clear the lever screw, so you can pull it to drop the cyl., but retain the pin (I know you knew this but others may not).
The reduction of the pin comes from the ROA. Even though the ROA has a gas ring/bushing, they left the "reduced pin diameter". Probably from earlier thoughts of a fouling remedy.
So, it's a marriage of Colt's fouling cut with Rugers "reduced dia pin" using my helical cuts.
It seems to work rather well. The first CAS pair I did this to won a state championship.
Mike
While I was typing, Arcticap asked his question. To that, no problems with reinsertion. The dia reduction isn't very much and there's a slight bevel. Take a peak at an ROA for an idea.