If this is the Colt 1878 Frontier model serial # 5100 , then it was produced around 1881.
The Liberty head design was used on over several different coins in 1878. Please post a new question with the coin's denomination, with the wording "What is the value of an 1878 US (coin denomination)?" e.g. What is the value of an 1878 US silver dollar? or What is the value of an 1878 US 10 dollar gold piece.
I think it is rather expensive as it is a collectible year and not many made with that amount of gold.
About a dollar.
Less than 100 to multiple thousands of USD depending on specifics
what is the current value of an 1878 silver dollar
$150
The Philadelphia issue (no mintmark) 1878 Trade Dollar is a Proof only coin with a retail value of about $1,000.00 but take it to a dealer for a assessment.
The only value is if there is silver in it, if not no collection value at all.
The US didn't mint any nickels in 1878. Please check your coin again.
A circulated 1878 Morgan silver dollar can be worth 32 to 156 dollars.
The Philadelphia issue (no mintmark) 1878 Trade Dollar is a Proof only issue. The coins have a retail value of about $1,000.00. Take it to a coin dealer for an assessment.
It is not very easy to find out the value of a 1878 morgan silver dollar, because the value varies from $20 to $46000 which depends on the condition of the coin. A specialist could help to find the value of this coin.