What years were the Remington model 31L made?

Hi i have a Remington model 31L 20ga and it was made in 1950
Description: Remington's first side ejecting repeating shotgun Introduction Year: 1931 Year Discontinued: 1949 Total Production: Approximately 196,000 Designer/Inventor: C.C. Loomis Action Type: Pump action Caliber/Gauge: 12, 16, 20 gauge Serial Number Blocks: 12 ga. 0,000 - 121,000
16 & 20 ga. 500,000 - 575,000 Grades Offered: 31A
31AP - Standard Grade
31B - Special Grade
31D - Tournament Grade
31E - Expert Grade
31F - Premier Grade
31H - Hunter's Special
31P - Police Grade
31R - Riot Grade
31 Skeet
31D Skeet Tournament
31E Skeet Expert
31F Skeet Premier
31 Trap Special Grade
31S-D Trap Tournament
31S-E Trap Expert
31S-F Trap Premier
31TC Trap (or Tournament) Grade
31T-D Target Tournament
31T-E Target Expert
31T-F Target Premier Variations: Model 31 New Improved in a Skeet Gun, TC Target Grade, Police Special, and Riot Gun
Model 31 New Improved Lightweight with Aluminum Receivers in a A,B,D,E,F, Skeet and Riot Grades (the letter "L" preceded the grade, ex. Model 31LA)
Model 31 Long-Range Guns in A Grade, New Improved A Grade, Trap Grade, Hunter's Special Grade, and Trap Grade (the letter "X" preceded the grade, ex. Model 31XA)