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I have wondered this for awhile, lets use for example .40 S&W. Why do the 155 grainers produce more felt recoil than maybe a 180? And I know this isn't the rifle forum but I must include that with rifles, it seems to be the opposite, the heavier the bullet the more recoil. Can someone clarify this?
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It is all about the conservation of momentum also known as Newton's third law of motion- MV = MV
In a nutshell, the rearward velocity of a gun (R in fps) of a given mass (M in pounds) is equal to the combined forward mass and velocity (V in fps) of the bullet (B in pounds) and the propellant (P in pounds).
Rearranging the equation the solution can be written like this-
(BV + PV) ÷ M = R
So, a 2 pound gun firing a 230 gr. (0.0329 pound) @ 835 fps with a 5 grain (0.000714 pound) charge of propellant @ 4,500 fps would have a rearward velocity of....
[(0.0329 lbs x 835 fps) + (0.000714 lbs x 4,500 fps)] ÷ 2 lbs =
15.34 fps.
You can also figure out the KE of the recoiling gun by using the equation ½mv
2 which gives you-
½mv
2 =
7.31 fpe