I would like point out that the self-appointed and anointed masters of all that is M1 Garand at Fulton Armory recommend not reloading for Garands (or anything). I think this is for many reasons, one being that they probably see many Garands with bent op-rods because of some of the stuff I am reading in this thread.
To begin with, let's examine what makes Garands special for reloading purposes. It is for one reason: the relatively narrow port pressure parameters that the rifle operates within.
Port pressure is the amount of pressure at the gas port, located about 3/4" from the muzzle. Too much port pressure may accelerate the op-rod too hard and bend it when it reaches its stop. Too little will provide insufficient force to push the op-rod to the point where the hammer is re-cocked. Much of the commerical .30-'06 out there has the potential to damage a M1 Garand. Avoid it unless you enjoy the fine art of bending op-rods back into shape.
There are two ways to modify a Garand to increase the maxim port pressure parameter. The cheapest and best way, but a somewhat tricky way, is to drill a hole in the gas cylinder just behind where the piston part of the op-rod is positioned when the hammer is just cocked. This way all the pressure needed to cock the hammer will be available, and then as soon as its cocked, the now unneeded pressure will bleed off. Another inferior and more expensive way to accomplish sort of the same thing is to buy a gas cylinder nut with a hole drilled in it or buy a surplus one and drill a hole in it yourself. You will need to find the right sized hole for the load you are using. It also doesn't bleed off unneeded pressure as well and may actually increase the lower port pressure parameter (narrowing the parameter).
If you don't want to get into this "modification" (aka improvement) work, then you MUST select your charge and bullet carefully. Fortunately the US Army Ordanance people already gave us good guidelines: duplicate ball ammo loads.
It is not overreaching to say that most new commercial .30-'06 is inapporate for Garands--it is! It is designed for bolt-actions, which don't even have a gas port! Often it uses the heavy bullets with slower powders in order to get maximum muzzle energy, range, etc. H4350 (and similar) is a slow powder, designed for magnum rifle cartridges, and is inappropiarate for a Garand. To have the port pressures in a safe area a very light bullet would be needed and a light bullet would not provide the inertia needed to "cork-up" the power and allow it to "get going" and produce a good pressure curve. I suppose a MEGA crimp could be used, but this will distort the bullet and probably impair accuracy. Or perhaps a magnum primer. But this is all very unsure. Why not just use a more appropriate powder and sacrifice, lets say, 200 FPS?
The best powder for the beginner reloader of a M1 Garand is H4895, since this powder is an analog of the millitary powder the Garand was designed for. The best bullets are in the 150-173 grain (also ball) area. Also, the maximum charge of H4895 in a Garand should be a might bit lower than what a typical reloading manual will list as a Max load. Usually the starting loads are where the max is approximately for a Garand.
Ball ammo went at about 2700 FPS out of a Garand with a 150 grain bullet. A heavier bullet should be slightly slower. Get some Greek .30-06 from the CMP. At $0.50 a pop (and on en-bloc clips), its the best deal out there except 7.62x54R surplus. Actually, don't buy the Greek stuff, because I would rather buy it myself. If you want to spend more money per round, Both Federal and Hornady make .30-'06 for Garands. The Hornady uses quality bullets and is sold (at a discount supposedly) by the CMP. I have never used the Federal, but I am confident it is good stuff. It better be at $1/round.
My recipie: HXP (Greek surplus, RCBS primer pocket swaged) brass full-length resized with Lee dies. 43 Grains of H4895 with a 168 Grain Hornady match bullet seated to max OAL that will chamber and then backed off ten thousandths. It is best to prime anything with a free-floating firing pin (M1A, Garand, AR-15, later SKSs, and many, many others), with harder primers or even primers that are designed for free-floating firing pins in order to help prevent slam fires (of course correct firearms safety and proper handling will completely prevent this). I use CCI, the hardest that are available to me. Winchester would be my second choice. The softest primers are Federal and should be avoided. Supposedly the Federal .30-'06 for M1 Garand has special primers, and this would seem to suggest that Federal knows that their primers are soft.