Aside from the leading scope manufactures are there any other names that are proven to function under magnum recoil rifles? Alpen Outdoor Corp, Barska, Konus USA Corp, Mueller, and Optronics Inc are some other names I have come across in research. Also BSA and Tasco have a few higher end models that looked decent. I'm looking for at least a 6x20x44 power or better with target style adjustment knobs while maintaining a budget of about $450-500. Can anyone shed some light on this situation?