Midway Shooting Supplies good news
Midway Shooting Supplies has M1A Checkmate 20 round magazines in stock for $27.99 each and you are limited to two.
Jump on them if you want them.
They also sent me a notice they had shipped two 20 round magazines for my LR308 for $26.99 each.
I don't know if any of those are left but mine have been on order for a LONG time. If you need them, you might want to check.