It's the momentum(m*v) that results in recoil. Conservation of momentum means the gun must have the same momentum as the gas and lead lost. The lead carries a loy of momentum, but so does the hot gas. If the gun is heavier, it's speed will be proportionately less.
Chas... if you get a stock that has more of an angle than the original stock, it will reduce felt recoil. The reciever will sit higher when the guns sholdered.
You are correct. Give me a "DUH"! for the equation.
action = reaction. Give me an "A".