I am often asked "how do I join the CMP" to buy a Garand.
It is a simple process however it can be intimidating.
First there is no CMP membership, rather some qualifications one must meet to buy firearms and ammo from them.
The easy answer is read the Eligibility Requirements directly from CMP here: http://www.odcmp.com/Sales/eligibility.htm
But I'll try and simplify it below.
1. Proof of U.S. Citizenship - This is an easy one a copy of your birth certificate or passport (you should get a passport if you don't have one anyway). Make a copy of this and put it in your packet.
2. Proof of Age - same as above in most cases. You must be 18.
3. Membership in CMP Affiliated Organization - This is perhaps the most complicated of the requirements. First Check and see if the range you may already belong to covers this requirement here: http://www.odcmp.com/clubs/searchclubs.htm
If your club is not listed and you are not a member of the any of the special affiliates below the easiest thing to do is join the Garand Collectors Association (GCA) its $25 and you can join online here GCA sends a list to CMP of members so you can order before you get your card in the mail. They have a nice quarterly magazine.
These special affiliates include: Congressionally chartered veterans' organizations such as the VFW, AL, DAV, MCL, etc. U.S. Military services (active or reserves), National Guard, to include retirees. Professional 501(c)3 law enforcement organizations and associations such as the FOP, NAPO, NSA, etc.
4. Marksmanship or other Firearms Related Activity - Easiest thing here is to include a copy of your Concealed Carry License.
If you are from one of those communist states that would rather see you get beaten to death than defend your self CMP lists some other options on their site including having a "Range or club official" or an LEO fill out this form for you http://www.odcmp.com/competitions/forms/marksmanship.pdf
Shooting in a CMP match also fulfills this requirement. Most clubs have club rifles you can use and will be happy to let you borrow anything you need.
If you are active duty military #3 and #4 are met for you.
5. Be able to legally buy a firearm - this should go without saying. If your plan was to use a CMP Garand for drive by shootings you will have to look elsewhere.
6. Fill out and get this form notarized - http://www.odcmp.com/Sales/pdfs/1orderformfillable.pdf.
Stuff everything in an envelope and mail it in with your check. Then comes the hard part..... waiting for your rifle to be brought directly to your door step.