Most likely the stock and handguards are the problem.
The most common problem if you are having accuracy or a wandering zero troubles is the handguards.
First check out the upper handguard. The gas cylinder should not be tight against the handguard. The handguard on a rack rifle should be just slightly loose. If the gas cylinder is putting pressure on the upper handguard you WILL have serious problems. You will have terrible accuracy and a different zero when the rifle warms up.
The lower handguard will cause the exact same problems if it is too long and putting pressure on the reciever. If it is touching the reciever trim some wood untill there ia a small gap.
Also the lower handguard should "float" You should be able to slip a piece of paper between it and the barrel.
If not remove some wood untill it does. The Clip that holds the handguard to the barrel should be the only part that touches the barrel.
While you have the lower handguard off place the rifle back in the stock and lock the trigger group back in.
Look down inside the stock and make sure the stock is not touching the barrel or OP rod. Once again use a dollar bill or a piece of paper to run along the stock to make sure there is no contact.
Also after you put your handguard back on make sure it does not touch the stock.
These quick and easy checks and mods can turn a really poor shooting Garand into a nice accurate rifle.
My latest Garand, a Dane with a like new VAR barrel, went from about 12 MOA with a huge different zero from hot to cold to a good better than two MOA shooter with the same zero from cold to too hot to hold.
Thanks for the info. That was a good quick summary of a few things to check.
I agree. Stock and handguard fit is at least 40% of the accuracy of the Garand.
You can have a fairly worn bore and they will still be resonably accurate if everything else is right.
A very common problem I see a lot is that some people just can't stand the thought of the upper handguard being loose so they crank the gas cylinder down tight against it.
This causes busted handguards and a serious zero problem. Your zero can change as much as 12 inches elevation at 100 yards from a cold rifle to it gets hot from a few rounds.
Thanks for the info... I will be using it when fitting new wood to my Garand.