Once I clean my ML bore should I use a lube such as bore butter or petrolium based lube perhaps with teflon?

You can use what you want there are alot of good lubes out there. If you want to save a buck and help displace water use wd40. I've been using it for over 20 years now and have never had a problem. I keep my guns clean and store them in as dry aplace as posible, the wd also works as a cleaner.

Do what model722 suggests. That's exactly what I do.