As for just a M1A in 30-06, I do not think there has been just one produced just before. Having said that, the M1 Garand went via some experimentation immediately after WWII (and I feel even a bit in the war) to add a removable mag, which was the basis https://federal-30-06-for-m1-gara66431.fare-blog.com/18410286/facts-about-federal-american-eagle-30-06-for-sale-revealed