Only Colt knows.
www.proofhouse.com
We need more information to identify the model. Colt's original single-shot derringers were in .41 caliber, not .22. They did make small single-shot derringers in the 1960's in .22 cal, but they did not have the markings you describe. www.countrygunsmith.net
Proofhouse.com has serial numbers for Colts. Your description is so vague as to be almost useless. Price range could be 500-10000 or more.
there are different model colts. what is your model, caliber and overall condition. serial number would help...............
Jim Harbaugh was the starter and Paul Justin was the backup. Kerwin Bell also saw action at QB for the 1996 Colts.
San Diego
DO NOT ATTEMPT TO DO THIS! It is unsafe and could result in damage to the firearm and/or injury or death to the shooter and/or bystanders. Always stick to the cartridge for which the gun was designed.
Six. All revolvers, with the exception of one or two specialty peices, fired Six.
You will have to provide caliber and ALL markings.
San Diego
I think it was the colts
Impossible to answer without knowing the model, caliber and condition.