Value is too difficult to be accurate without seeing the gun. Condition which includes the amount of original finish and original configuration will determine value. Condition and age is also a factor. Auto 5's with recoil pads (other than Mag 12's) poly-chokes and compensators will reduce value. Recommend taking it to a gun shop for appraisal.
50- 700 usd
If you mean a 22LR, 200or so
300-500 USD.
50-500 usd
100-600 usd-
$350
100-1000 usd
Browning never made a Model 51 shotgun.
500 uSD
0-400 usd
50-500 usd
Impossible to value with just the sn.