I have used all of the mentioned products at one time or another. The best recoil pad is a Simms. Pacmayer is good. Magnaporting is not as effective as an expansion chamber muzzle brake. And there is sometimes a gas cutting issue at the front of the slots that can have a detrimental effect on accuracy. The mercury cylinders soak up a lot of recoil, but make the gun not only quite a bit heavier - but also screw up the balance of the weapon. The gun becomes very butt heavy. Not good for quick shots.

I would recommend staying away from a lightweight gun in this caliber. Get a rifle that weighs about ten pounds with scope and all. Put a Simm's Vibration Lab recoil pad on it. Do your sighting in and load development off of a Caldwell Lead Sled. Forget the Magnaport and the mercury.