scottish wrote:
I have a Mossberg 500 and do not use it because it rips off my shoulder. Looking for advice I was really interested in the SA-20 with the hope that it would eliminate that. All reviews point to yes.
There is no formula for felt recoil and there cannot be. That's just a matter of opinion.
Actual recoil is another matter. It is easily calculated, see
http://www.shooterscalculator.com/recoil-calculator.php . No Mossberg 500 should 'tear off' anyone's shoulder. You reduce weight of the payload and velocity of the payload, and recoil drops in concert.
The SA-20 (and TriStar Viper
https://www.tristararms.com/series/viper-g2/ ) are gas-operated and are soft-shooting for everyone with common 7/8 oz. target loads.
The softest-shooting 20 gauge I've tested in years is a Remington 11-87.