As for just a M1A in thirty-06, I do not Consider There was 1 built just before. Having said that, the M1 Garand went through some experimentation after WWII (and I think even a little bit during the war) so as to add a detachable mag, which was the basis https://donovanepyhx.thechapblog.com/19883021/examine-this-report-on-30-06-garand-ammo-difference