Interesting “Zombie” thread from 2004.....

I was not convinced that the OP’s calculations were correct as to his original question regarding .577 BPE recoil and the mentioned .577 2 3/4” 90 Cordite 650 grain bullet load

- The .577 90-650 equivalent load (1950’/sec) in an 11lb10oz rifle would be ~92.5 foot pounds (not 66) This is notwithstanding that the .577 90-650 was NOT a “Light Cordite” or Nitro for Black....it was a full Nitro loading for Nitro proved rifles.

- A .577 2 3/4” BPE was variously 6 Drams with a 520-570 grain copper tube or solid bullet. An 11lb 10oz rifle with 6 Drams of BP would have ~74.5 foot pounds of recoil with the 520 grain bullet. As Sarg mentions above, the usual NfB load was 75 grains Cordite with the 650 grain bullet.

- the mentioned Ruger No.1 in factory .458 Win Mag would be around 67 foot pounds depending on weight.

My 1902 Webley .577 3” weighs 11lbs 6oz and while the recoil of a 90-650 equivalent load @1950’/sec is, to my notion, not as “sharp” a whack as a Ruger No.1 .458, it is a whole lot more recoil.
As an aside; the rifle would take it but I have no interest in shooting a modern “Full Nitro” .577 100-750 in my Webley. There would be, as the saying goes, “a loss of snot and enamel on both ends”.
- Mike