What mounts fit A BFR and hold up to recoil? I
have a 475L $ a 500JRH. I will probably try an Ultradot as some of you speak highly of them.
Thanks.

Magnum Research makes their own, for both size frames. Check here:

http://www.magnumresearch.com/...-short-cylinder.aspx

Thank you whelenite. I couldn't find it on their website but I've got it now.