Spencer’s rifle…..

I looked that up, I don’t think those are the same guns. According to this…

https://www.imfdb.org/wiki/Quigley_Down_Under

…the rife in Quigley Down Under was a single-barrel Shiloh Sharps 1874 Long Range Rifle shooting a .45-110 metallic cartridge with a 540 grain paper-patch bullet.

I found this…

https://www.rockislandauction.com/riac-blog/guns-of-1923-yellowstone-and-the-dutton-family-tree

According to that, a Sabatti or similarly affordable modern Italian model is likely the gun during 1923’s dangerous game scenes. It also says though the production gun is almost certainly neither period-correct nor of British make, Spencer’s rifle is probably intended to represent a British dangerous game gun of the era, such as a Holland & Holland Royal in .500/465 Nitro Express, a classic big game double rifle from the golden era of British gunmaking that an African hunter in 1923 might have used so I guess I can say mystery solved.

Which they used to wipe out American Elephants in the 19th century.

According to the link I posted above a couple weeks ago, it's not an elephant gun. It’s based off a Nitro Express.

Besides.... When I think of an elephant gun, I think of the 12 and a half pound William Moore & Co. 8 gauge shotgun shooting solid slugs that Bert uses in Tremors which is much, much bigger than what ole Spence uses.

https://www.imfdb.org/wiki/Tremors_(1990)#William_Moore_.26_Co._8_gauge_shotgun

500/465 or .416 Rigby maybe or .477 Jeffreys . . . they were all popular (most still are)