This is a Marlin Model 336SC (Sporting Carbine) in .219 Zipper, serial number U19751.
Year of manufacture: 1961. Marlin used a single-letter prefix on 336 serial numbers from the late 1940s through 1964; “U” corresponds to 1961.
•  Micro-Groove barrel — Marlin introduced Micro-Groove rifling in 1956; the barrel marking confirms it.
•  20-inch barrel typical of the SC “Sporting Carbine” configuration (versus the 24-inch 336A rifle).
•  Pistol-grip walnut stock with white-line spacer at the buttplate (a 1957-and-later feature).
•  Gold-plated trigger (introduced 1959).
•  Receiver drilled and tapped for a scope (standard from 1956 onward).
•  Period Marlin/Micro-Vue style scope with gold-finished rings.

 

Curio/Relic: Yes
Rifle Caliber: .219 Zipper
Manufacturer: Marlin
Model: 336
Serial Number: U19751
Barrel Length: 20”
Condition: Very Good
Metal Condition: Very Good
Wood Condition: Very Good
Bore Condition: Very Good
Barrel Type: Round
Action: Lever
Triggers: Gold SA
Stock: Walnut
Fore End: Walnut
Butt Pad: Marlin
Finish: Blued
Sights: Open adjustable
Manufacture Date: 1961
Item Location: Mn
Optic: Marlin Micro-Vue