For the "standard" NEW Model (with transfer bar safety) Blackhawk in .357 Mag, current retail values range from around $200 in fair condition to around $480 in Excellent condition. If New In Box - $500 to $550. Be advised that there are a couple variations that can bring more value.
You will have to call Browning with the serial number.
A handgun.
Magnum
OLD!
On the butt
Check on the butt.
Impossible to answer without the serial number.
Feb.1984 with the serial number that you have provided.
If you mean serial number 27,078,977;then it was made in 1973.
Your serial number indicates that it was made in the year 1973.
About 1968/1969.
You will have to call Colt or provide the serial number.