If the Ruger website is up, it has sn data.
Ruger's website has extensive sn data.
100-500
Depending on condition, and WHICH version of the M77, between $250 and $500.
Unknown caliber. Contact Ruger
The Ruger website, under customer service, historical data, rifle, M77, will have the serial number ranges for each year of production.
Remington 700 308?
50-700 usd
Long
100-400
Strong enough for factory loaded ammunition and hand loads that don't exceed SAMMI standards.
Request an owner's manual from Ruger on their web site or take it to a gun smith.