Depending on condition, $450-$500. If you have the 22LR and 22 Mag cylinders, box, etc, add another $100.
Could not find a Colt frontier scout with serial number 56599P, but a Colt frontier scout with serial number 56599F was made in 1959.
The Colt Frontier Scout with that serial number was made in 1965.
Your frontier scout was made in 1963.
Your colt frontier scout was made in 1968.
No serial number provided.
A Colt frontier scout with serial number 127580F was made about 1960.
Colt frontier scout with that serial number was made in 1962 per proofhouse.com
Your Colt frontier scout with that serial number would be 47 years old, made in 1964.
Your colt frontier scout 62 was made in 1966.
To answer the question we'll need to know more about this pistol. Is it a revolver or a semiauto? What model and caliber? I found a Colt frontier scout .22 with that serial number made in 1962.
1959
Your colt frontier scout .22 mag was made in 1962.