It has been mentioned here before, and it is the most sensible answer. Go to your local musical instrument retailer (or order it on-line) and get a ring that is made for the hole in the bass drum reso head. It comes with a template. Trace it out and cut it as neatly as you can with an X-acto or utility knife. The ring has an adhesive tape that is very much like an epoxy based glue so that the ring will stay positioned without buzzing because of vibrations and also it adheres the head to the ring so it will keep any bad cuts from growing into a tear later on down the road. It's simple, it works, end of story.