Re: P4F reticle question...
From what I remember, L is the distance from the top of a male head to the bottom at 100y, M is the same only 150, N is 200, O is 250.
Then they do the same thing from the top of the head to the belt line on a male, only at further distances, and I don't remember how those correlate.
For a competition shooter, I don't know where it would have a ton of value, unless you are shooting IPSC silhouettes.