Re: Rear lugged vs. non M1A?
I have put a few (thousand) rounds thru rifles with and without lugs. The unlugged rifles will shoot just as well as a single or double lugged rifle if it is correctly bedded into the stock.
That being said, a single lugged rifle (what the Navy used for DMRs) will maintain the accuracy of the bedding job longer. No more skim bedding after 3-5000 rounds. More like re-bedding with a re-barrel.
The double lug rifles (the Navy Match Grade A) could be (carefully) removed and replaced in the stock without a significant loss of zero. When bedding double lugged rifles, you wouldn't put tension on the front ferrule. With the stiffer McMillan stocks, the barrel/gas cyl assembly was almost free-floating.
Remember, with both single and double lugged rifles, the lugs have screws that are pillar bedded into the stock, just like a bolt gun.