260Rem
Try one of these.
These can be mounted on a weaver or picatinny rail (20018)
https://www.youtube.com/watch?v=xcO2XfFTBDQ
http://www.sportingshooter.com.au/gear/kahles-red-dot-sight
The 20019 model requires a separate base that can be milled into the top rib.
Very light & they can withstand the recoil easily