Friend, bore condition is EVERYTHING. If you have a good bore, you have a rifle which can be made to shoot.
I'm shocked that somebody hasn't jumped up and screamed "Check the headspace! Check the headspace! The sky is falling!" by now. Garands were so precisely made that VERY little fitting need be done; most parts are a dead fit, even bolts coming in so close to perfect that very often they can be switched freely with no troubles.
Remember, the front handguard is SUPPOSED to be loose! Tightening the rifle up at that point will ruin your accuracy before you have the second clip shot off. It NEEDS play.
Another point to consider: the clamping action between the metal and the woodwork also is critical. The trigger group clamps onto the receiver group, sandwiching the stock between them. This is supposed to be TIGHT. If this is the least bit loose, you can tighten it up with skinny little shims of cardboard (the end-flaps from a Player's package is perfect). The thing should solid up as you are clamping the trigger group onto the rifle; the last 45 or 50 degrees should be TIGHT.
A trick you can do with a Garand is to put your sights off a bit. The front sight is 4 minutes wide, the rear sight is calibrated in 1-minute clicks. Put your rear sight 2 minutes off to the left and aim with the upper-right CORNER of the front sight. Works: my rifle will shoot half-inch groups like this at 100, off the sandbags, of course.
Hope this helps.
Have fun!
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