“The rifle in question has a tubular magazine located under the barrel, as do many other lever action, slide action and semiautomatic firearms. Partially working the action allows a spring in the tubular magazine to push a cartridge back onto the lifter. Continuing to work the action allows the lifter to lift the cartridge up in line with the barrel so it can be pushed into the chamber.
So far as I know, it’s a legitimate term, although there may be others.”
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Correct. That explains the lifter. But it looks like an odd combination of rifles. In pictures of the right side of the rifle, it is a side load, and it has the under barrel magazine. In the xray it shows a rear tube feed with a cartridge still in the tube in the stock. Looks like a .45 long colt or maybe a .44 .
Was the 1873 capable of being loaded either way? I am only familiar with replicas and modern lever guns, which I have only seen to be either one way or the other.
If you look at the picture in #4 you will see a lid in the middle of the butt plate. Small items or extra ammo could be stored there. The Spencer was the most common stock loading rifle of the day, all 1873’s were side load into the under barrel magazine tube.
The cartridge is likely a .44-40 (44 W.C.F), as the 1873 was not chambered (originally) for the .45 Colt.
That’s not a rear feed tube.
I don't think the 'tube' in the stock is an actual magazine, but perhaps just a place to keep a few spare rounds... The actual magazine is the tube under the barrel as with modern carbines. If you look at that x-ray upthread, the bored hole in the stock stops well short of any mechanism...
That is not a feed into the tube. Some had cleaning rod storage in the stock. Some would use that space to store extra ammo.
https://www.gunsamerica.com/blog/shooting-history-winchester-1873-old-gun-review/
“Was the 1873 capable of being loaded either way?”
No. I agree with what’s already been posted.
The opening in which the cartridge can be seen doesn’t extend into the action so a cartridge couldn’t get to the chamber from there.
I think it was used for storage, in this case of extra cartridges.
The butt plate looks more substantial than anything I can find in a picture or exploded diagram on the web, so maybe it has a hinge or opening for access that can’t be seen in the x-ray.