Welcome to the Forum
The 586 L-comp is a 7 shot revolver
First question, did you buy this new or used?
Next question, if used was the original factory box included?
Last question, if you have the box what is the 5 or 6 digit product code printed on the end label?
Naturally pictures of the firearm, and end label would go a long way toward a solution
If you purchased this used, a previous owner might have changed the cylinder out for the 6 shot variety.