What a Garand is worth is largely dependent on what you want to do with it. Collectors want certain things. Competitors in Garand matches want other things.
Springfield Armory and the other makers were revising the design slighly on a regular basis right up to the end of production, and collectors know what revision number is correct for a particular part on a receiver with a certain Serial Number. Rifles with all the 'right' revision numbers marked on their parts are known as "Correct," which commands a higher price. Correct and Original gets a much higher price. Some makers are very hard to find, and are in great demand, such as International Harvester.
Some makers are just in a lot of demand, such as Winchester.
Some makers made their M1's early, and most of their examples have been rebuilt multiple times, so a pristine all-original example is particularly valuable, such as Winchester.
Some makers made all of theirs late, so their examples are more likely to be original, such as Harrington & Richardson.
Some variations were not made in quantity, or were mostly modified to the later patterns, such as National Match and "Gas Trap" rifles.
Various stampings in the wood were done at various times, especially original acceptance, rebuilds and inspection. Presence or absence means a lot to collectors.
Some examples have perfect replacement barrels, which adds a lot to functional value but little value to collectors.
A lot of M1 rifles were cleaned carelessly, and damage to muzzle rifling resulted. If a M2 cartridge gently placed bullet down into the muzzle goes in right up to the cartridge case, it is very unlikely to shoot well. If there is a bit over 1/4" of bullet showing, it's a good muzzle.
A tightly fitting stock, without oilsoak, is important to accuracy. Push your thumb against the side of the rear of the receiver, and if it moves, leave it. Unclamp the trigger guard and if it does not take a lot of pressure to reclamp, leave it.
Safe Queen owners
Some things, such as American 'Black Walnut' stocks are preferred by many over American Birch, and I don't know anyone who really likes Italian and Danish Beech, and prices reflect these realities. It is nice when each of the wood pieces match the others.
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