Rimfire ID needed

I need some help Id-ing these two cartridges.
On the left: No headstamp. Dimensions are: bullet dia: .487; rim: .633; base: .550; neck: .532; case lgth: 1.735; aol: 2.24
On the right: “U” h/s; bullet: .523; rim: .644; base: .560; neck: .527; case lgth: .963; aol: 1.77

My guess is that the left is a .50 US Carbine, and the right is a Spencer. But I wouldn’t hang my hat on either one.
Any ideas? Thank you.

Twigbender, you called those. Measured several of mine and yours are close. Dimensions of rimfires vary so much at that time it is a wonder some fit the chambers. Without SAAMI guess gun makers made the largest chambers they thought any cartridge of a certain design would fit and hoped an undersized one would not rupture. The Spencer would be a 56-52. Some makes of the 56-52 had soulders which was actually a bullet crimp the shoulders depending on make are all over the length of the case a few were roll crimped.

In my opinion the one on the left is a Norwegian 12 x 44 R Remington m/71. All its dimensions match and the bullet shows the typical knurled cannelure.

I agree with Fede the first one looks like a “50 Norwegian” Remington.


Thank you, guys. Now that you mention the “50 Norwegian Remington” I recall someone back in the early 80s telling me that’s what he thought it was. I haven’t been able to find that cartridge in any of my lists, so I assumed that he was just blowing some smoke. Maybe he was on to something!
Thanks again!