There is no lever under the loading gate. There is an ejection rod alongside the barrel.
Your colt frontier scout was made by colt in 1959.
Yes,they did.You probably saw one in movie ''The Good,the Bad,and the Ugly'' While Colt factory conversions were without loading levers with cartridge ejectors,most people in Old West did not send Colt to factory to convert,they were converting them at gunsmiths,and they started gunsmith converting as early in the Civil War.And those gunsmiths did not have cartridge ejectors,so they kept loading lever. And another option to leave loading lever were so called "Thuer conversions" , which were very rare,and they appeared as early in the late 1850's.They used cartridges without rims and they used loading lever to seat that cartridges,but it was much faster than loading with loose black powder.
Your colt frontier scout was made in 1968.
Your colt frontier scout 22lr was produced in 1960.
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 a Qor F suffix was made from 1957-1970.A colt frontier scout with a K suffix was made from 1960-1970.A colt frontier scout with a P suffix was made from 1962-1970.And the colt new frontier scout with the cross bolt safety was made from 1970-1977,and reintroduced in 1982-1986.
Your colt frontier scout 62 was made in 1966.
That Colt frontier scout was made in 1959.
Never
Look on the grip frame under the grip panes and on the bottom of the frame under the barrel.
The Colt Frontier Scout with that serial number was made in 1965.
Proofhouse.com has Colt sn data.