An unmarked large rimfire cartridge

This is another cartridge found among a box of stuff left by a friend.

No marks except for the three crimps in the case and two o the head.

Bullet dia. at the case mouth is 0.502.

Base dia. is 0.562.

Rim dia. is 0.642

Rim thickness is 0.070

Case length is 1.151

Cart. OAL is 1.603

Does this qualify as a “necked cartridge”? The closest I can come up with is 56-52 Spencer necked but the Case length and OAL are wrong.

It looks like a 56-50 Spencer by CD Leet. Not a bottle neck just the way they crimped to bullet.