Exile Machine in TX sells mags to Calif. in "rebuild kit" form broken down.
Some 10 rnd M1A mags here on pg. 2:
https://www.exilemachine.net/shop/ma...2/index-2.html
44Mag.com does sell M1A/M14 mags & floor plates (Checkmate brand), but they are out of stock like everyone else except for 5 rnd :
http://www.44mag.com/category/m1a_m14_magazines_usgi
AND, here is a short FAQ on M14 mags. It has some critical info on mag body wall thickness specs and follower hardness - a very good read:
http://m14forum.com/reference/40552-...magazines.html