I found that CMP holds these clinics and shooting matches, but I only saw clinics where you could only learn for the Springfield/Garand? I'm probably mistaken but wouldn't that mean you can only take those rifles?
GSM Clinics/Matches: Garand, Springfield, Military or other as issue Military rifles used prior to 1954. AND MM or Modern Military.
They are called Garand Clinics but they NOT LIMITED Garand's, Springfield's or any other "one" rifle. They are clinics that cover the CMP Vintage Rifle Program which now include "modern military". The Vintage rifle covered pre-1954 rifles but the Modern Military covers post 54 rifles such as the M14, AR. AKs, SKSs etc. (non match, non-full auto).
To save time and confusing, when I conduct a clinic I ask the attendees what rifles they will be using an limit my class to those rifles. I have, nor have I ever heard of, a CMP Master Instructor, ever turning down any one regardless of what "safe" rifle they want to use. Most if not all provide loaner rifles to those who don't have rifles.
Please PM me if you wish any further information on the CMP GSM Clinics, matches or the CMP Program. If I don't have the answers I'll stir you to those who will have them.
Mosen's are quite popular as they provide a reasonably cost rifle well suited for the CMP Vintage Rifle games. The problem with the Mosin is not the rifle but that few people will take the time to learn it. That is what the Clinic is about.
Just for information one of the first Clinic/Matches I conducted after becoming a CMP MI was won by a buy a guy who went out the night before the match, bought a Mosin and some surplus ammo. He never fired the rifle prior to the match.