Thousands of high-power/service rifle shooters who use M1A rifles (dying breed now) figured out how to get the best accuracy from this type of stock/barreled action interface:
a) bed the receiver so it mates with the stock, like you'd do on your bolt action rifle. Most of these rifles are very sloppy at the back end.
b) consider bedding it so the barrel band (gas block on the Mini-14) exerts consistent upward pressure on the stock when you lock the trigger group in.
I've done this or had it done on a half dozen M1As. Unbedded M1As tend to shoot 3-4 MOA, just like a mini. But even with a skinny barrel, a bedded M1A is a 1.5 moa rifle. With a heavy barrel they're sub MOA.
