As for a M1A in 30-06, I do not Assume There was a person manufactured before. Having said that, the M1 Garand went by some experimentation soon after WWII (and I believe even a bit throughout the war) to include a detachable mag, which was the basis of your M14. https://30-06garandammodifference84816.blogchaat.com/18345955/30-06-ballistics-168-grain-an-overview