Here's my question and it's root. I've read countless times that
for African dangerous game penetration that the 416 Rigby
"formula" is essentially ideal. Velocity 2400 FPS, .416" diameter
bullet with sectional density of .338 resulting from 410 grain
bullet.

It's generally fired from a rifle that's unloaded, un-scoped weight
is right at 10 pounds per my research; maybe a few ounces less.

For essentially the same recoil as the above, what weight should
a rifle be that's firing a .375" cal. bullet at 335 grain weight
with a velocity of 2400 fps? Hopefully a pound and a half can be
saved? Thanks! {rimmed / flanged case will be used - Farqharson
action rifle}

More like 3lbs!!!

I could not find a 335gr 375 boolit so i took a 350gr Woodleigh and trimmed the weight down.







In both cases the recoil is @37 ft/lbs

{Opening post phrasing has been tweaked a little, NO numeric changes}

Hi Dane,

Thanks for all that calculating. Now I think that I understand
you to be reporting that you've determined that the rifle for
the .375 caliber could weigh three pounds LESS than the
ten pound 416 Rigby rifle! I am not familiar with how to run
through all that figuring that you did by the way, I am impressed!
A guy can order bullets from www.gscustom.co.za in basically ANY
diameter and at ANY weight. Gerard there does some math to tell
you what twist rate you'll need for stabilizing your custom bullet.

In the small pics there are two important fields for you.

The first is:
The second from the right top "Energy of Recoiling". The 416 set the bar at @38 ft/lbs and i then matched the 375 to get the same recoil energy.
Second field is right bottom "Total gun Weight" in yellow.
The only difference being the lighter gun.

So from 10lbs to just shy of 7lbs to get the same recoil.

I really appreciate the guidance!
Thank you again.

Glad to be of service mate!

When your shooting at a Cape buffalo, you don't feel the recoil. AIU

I believe that when shooting at DG the recoil is not felt.

But at the same time that does not suggest that we want
a 5 pound 416 Rigby nor a 3.5 pound 375 H&H Mag.