I have a Savage FCP-K in .308 caliber and this particular rifle comes with a muzzle brake. I was having difficulty finding a set of rings that would stabilize the scope beyond 20 to 30 rounds. There is significant back pressure due to the muzzle brake, and another set of rings that I had would require me to re-tighten and re-zero the scope repeatedly. These rings have stabilized my Vortex Viper 6.5 to 20 power scope with no problems at all. I highly recommend these rings for anyone who needs exceptional scope stabilization.
These rings are very well made and just as good if not better than 100 dollar rings. I have used these on my M4 as well as my 308 sniper rifle and never had a problem with an optic moving! They are worth every penny!!