This one right here is the heaviest recoiler I have and have ever shot. It weighs 4-lbs and shoots a 525 just under 1,600 fps. You need a hardhat and a saddle to shoot it:
My next two kickers are my SRH in .500 Linebaugh which weighs a couple of ounces shot of 3-lbs, but right behind it is my 4-inch Redhawk in .454.
This one (BFR in .500 JRH) is bad when the 425s and 440s hit about 1,450.