I have two of these 15 round magazines for the M1A/M14. I used to have a Springfield rifle, bought these and subsequently lost them in storage for years. I am 99% certain they are Checkmate brand, but you can see the barcode on them. They have never been taken out of the oil / wrapper.
Looking for $80 shipped for both of them. Payment via Zelle, PayPal, Venmo or snail mail.
Let me know if you can use these.