I have a Garand I got from Springfield Armory, Inc. (new production) and it's a different thing than a CMP Garand, even though most of its parts are WWII or Korean surplus. Even so, I checked headspace, made up dummy rounds and checked feed and clip ejection, took it apart and lubed it (as it was dry from the factory), dropped bolt on brass w/ primer only to check for slam fire, THEN took it out and shot it.
The CMP statement is probably a liability thing...but I'd find a knowledgeable Garand person in your area to look it over at the very least. Surprisingly, many gunsmiths don't know the first thing about Garands (!).
What little I know is that he should look at
1. Headspace. If this is excessive, it can be dangerous. If its too little, it can prevent bolt from closing fully and that might be dangerous if worn parts permit rifle to fire anyway.
2. Firing pin fit in bolt and amount of protrusion. Sticky or too much protrusion can be dangerous.
3. Receiver bridge and firing pin wear at rear - this is a Garand design feature which prevents firing pin hitting primer on inertia as bolt slams forward. Many old Garands have worn bridges, worn firing pins or both. Can be dangerous.
CMP has qualified armorers that go through these when they rebuild them, and they probably do all of the above checks (1 thru 3). Send them an email and ask if they check all that stuff. If they say they do, you're probably OK.
(A Garand is a machine as much as it is a rifle. I kind of enjoyed learning about the Garand checkout process...you might have fun learning about how to inspect a Garand to make sure it's safe, too.)
