Late 70's or so. Call S&W and they will tell you when it left the factory
50-125
it might be a model from 1975
No sn data available
The suffix of P7 to your serial number indicates that you have a Browning Nomad model pistol,which was made in the year 1967.
Ruger has sn data on their website.
50-300
If you can get it to work, the Ruger website has sn data.
50-126
Proofhouse.com
Browning.com has sn data under customer service.
Impossible to answer without a detailed description and the serial number.
50-250 USD or so