The Remington Model 12 is a slide action (pump) rimfire rifle. It is fed by a tubular magazine.

related:

• • • Remington Model 121 Fieldmaster

document(s):

• • • Remington Field Service Manual for Model 12-Model 121 Fieldmaster

gunsmithing note(s):

• • • Rear scope mount:
      • Weaver #43 ⇒ ¹
        • Brownells part number 955-010-043WB ²
        • Weaver part number: 48043
        • position A
    • Front scope mount:
      • Weaver #42 ⇒ ³
        • Brownells part number955-010-042WB ⁴
        • manufacturer part number: 48042
        • position D
    • …

1. Trevor Alt of Vista Outdoors was kind enough to share, via email, a scanned chart from the W. R. Weaver Company days that gives mount numbers for given gun models with placement specifications. This information is from that chart.
2. As of 6 Sep 2018
3. Trevor Alt of Vista Outdoors was kind enough to share, via email, a scanned chart from the W. R. Weaver Company days that gives mount numbers for given gun models with placement specifications. This information is from that chart.
4. As of 6 Sep 2018