Does anyone make a tool custom fitted for the slot in the mounting screw for the Ruger scope mount? I suppose I could just use a big screw driver, but I prefer to avoid marring the slot.

I use a Mossberg choke tube wrench.

It's a small, flat t shaped tool kinda like the Chevrolet emblem. It has a hole drilled in one end.

It could be hung around your kneck, put on a keychain, etc. It gives you plenty of leverage.

GVA

This is it:

http://cgi.ebay.com/Mossberg-Choke-Tube-Wrench-12-20-Ga...568225QQcmdZViewItem

GVA

Brownells has a kit for different scope rings. If you use a big screw driver, use a "hollow ground" tip.

I use a quarter.