Collectors value Garands in the following sequence; unmolested original factory built rifles, US arsenal rebuilt rifles, and lastly, restorations done by individuals in their home "armoury/workshop". Within each of these categories, the value is set by condition.
One can easily determine if a rifle is "parts correct" by scrutinizing the drawing numbers and makers marks IAW the Scott Duff books and then relating these to the receiver and barrel make and date. Parts correct rifles can either be factory built rifles in original condition or restorations where the restorer has sifted through various parts to make the rifle "correct".
IMHO there are very few factory original rifles in circulation. These rifles were in service for 30-35 years, and the vast majority were rebuilt one or more times while in military use. Rebuilds continued right up to the late 1960s ( I have a very nice Letterkenny rebuild of an Oct 1942 receiver done in 1969). It is interesting to look at the rebuild flow chart which was used by the US arsenals as this offers a good insight as to why so few rifles are "parts correct". On receipt at the arsenal the rifle was completely stripped with ALL parts automatically going through an inspection and refinishing process and then into the inventory bins, except for the barrel, bolt, and op rod which followed the receiver through to the end unless any of these 3 key components were found unservicable and replaced during the inspection process. Following reparkerizing, the receiver and barrel/op rod/bolt combo (assuming these components made it through inspections) were then built up into complete, as new, rifles using either new or reconditioned parts from the bins. Any and all parts were used w/o regard to manufacturer or drawing number as all were interchangeable.
Those who carried a rifle in military service can attest to the toll taken on an individual rifle while in use by the soldier. Rifles were subjected to harsh use and weathering incl climbing in and out of vehicles, bayonet drill, hitting the ground to take up firing positions, parade square bashing etc., as well as shooting without regular cleaning. US military .30-06 ammo was made with corrosive priming compounds until 1952 and a lot of the corrosive primed stuff was used long after this date. This, as well as poor cleaning techniques, accounts for the high replacement rate of barrels. That said, original WW2 era receiver/ barrel combinations can still be found with the barrels in servicable condition, although this is the exception. Stocks and handguards were other fast moving replacement items as these were frequently cracked or broken in use. The vast majority of rifles were also re-parkerized one or more times as the finish wears off through handling and use by troops.
Time and numbers, as well as high grade appearance, persuades me that most "minty" (love that mouthwash flavor) "parts correct/matching" rifles that are seen these days are in fact restorations to one extent or another. I have restored many rifles from scratch with new barrels and wood and new or reparkerized parts and refinished wood and find it a great hobby. I have also put together a number or "parts correct" rifles, although availability of original stocks and barrels is often the limiting factor for a 100% restoration. There is absolutely nothing wrong with a restored rifle as long as it isn't falsely portrayed as a factory original with the idea of inflating it's value. As far as values are concerned, my sense is that most people prefer a nice clean shootable rifle of WW2 vintage, so this is where the money is, except for scarcer models like the M1C/M1D sniper models which have a market of their own. All said, supply and demand, coupled with condition and originality, will ultimately determine the market value.
