In game the T-62M-1 and T-62 models use the same gun sight. However the optical zoom of these sights are different, the T-62 has a 3.5x-7.0x zoom sight (the original sight) while the T-62M-1 has a 8x zoom sight.
The T-62M-1 should either have its primary sight changed to the auxiliary sight in the roof or have the zoom values on the main gun sight changed to correctly match the 3.5x-7.0x found on the T-62.
I think it would be better off just having the gunners optic stay the same but with the correct zoom level applied. But regardless of whether the main gun sight gets its correct values or the auxiliary gun sight is selected as the main gun sight the model needs changing because of its inaccuracies right now.