1912
It's a pump action 22 rifle.
It's a model 12 from 1912.
If it's a unmarked pump it's a model 12 manufactured in 1912
Late (almost certainly December) 1916
What Model 51 pistol or a rifle and what model?
Union Metalic Cartridge Co. is a division of Remington UMC purchased Remington Arms Co in 1912 and became Remington Arms UMC.
1913
1920
1913
Depends on what you mean. UMC is a brand of ammo made by Remington. UMC = Union Metallic Cartridge By Remington
Made in 1908
Early 1909