You'll enjoy the gun. I bought one from the CMP and was (am) very pleased with it.
All the previous provide solid advice. I use the gas plug in the linked previous and like ability to safely use commercial ammo. I use it in the single shot mode and brass doesn't go into the next lane.
A word of caution for you about M1 thumb. It can happen but if you pay attention, the bolt will come forward when you load it but it should stop it's forward motion when it begins to strip the top round. You then bump the bolt forward to complete the cycle and off you go.
However, a friend of a friend of my 2'nd cousin
got his thumb caught in the action when he had it on the bench rest to service it. The bolt was back and the DA accidently bumped the follower
the bolt slams home with authority believe me....er....DA and it basically captured his thumb on his right hand. So there I...er.. DA was facing backward trying to pull back the bolt with his left hand. Awkward to say the least. Lost the thumbnail.
Enjoy your upcoming purchase!
Hobie also known as DA