Aye Dew Math

Gun Stats gives formula to calculate the ST and Rcl.

Rcl = 1 + [(V*PW*Ar*Hl*Mb)/(Ewt+Sgr)]

V is muzzle velocity in fps
PW is bullet weight in lbs
Ewt is the empty weight in lbs

Ar is a constant based on the action.  0.4 for guns with reciprocating actions, 0.5 for not.

Hl is a high/low pressure constant.  1 for every gun except guns that use a high/low pressure round, like a 40mm grenade launcher.

Mb is a constant for muzzle brakes and recoil reduction systems.  1 for a bare muzzle.

Sgr is a constant for the stock configuration.  5 for stocks with pistol grips, 4 for Fudd stocks.  5 for normal handguns, 4 for handguns like old flintlocks.

I was not getting the numbers I expected and it was because I'd read the description of Hl wrong and used 0.1 instead of 1.

This feeds into the ST calculation which is the square root of the square root of Lwt*Rcl*1,200 for handguns or 300 for long guns.

I think they did the square root of the square root instead of ∜ because most people don't have a button for that on their calculator and don't know to enter ^0.25 to get it on  a spreadsheet.

If you fail rinse, you're going to fail repeat in the lather, rinse, repeat test...