I had a vais on my first 300 wm custom with a #3 contour. It worked great with no complaints but I don't shoot a lot of prone. I currently have another 300 wm with #3 contour and in my opinion the vias felt like less recoil than the current microbastard I'm using. That said, if you have a heavy enough barrel to accommodate them, their are better options available for controlling recoil and staying on target. Precision Rifle blog had a very detailed objective comparison of muzzles brakes about 3 years back that should help give you some ideas. The review did not include the vais but i suspect that is because they are not used much in PRS competition. If you are looking for a brake on a hunting rifle, the barrel contour may limit your choices and as noted above, some of the available options would limit your ability to use a suppressor in the future.