I don't think you'll wear one out. Barrel maybe, if you shoot several thousand rounds, recoil/op rod spring probably. The rest of it is already over 75 years old and still going strong.
The delicate parts are the op rod - if you run powders outside/above the design burn rate and cause higher than normal gas port pressures. It's not chamber pressure than "kills" a Garand, it's gas port pressure.
A few years after WW2 they got to wondering why they never had issues with M1 Garands blowing up in combat (there had been issues with 03 Springfields after WW1 due to some heat treating issues).
They decided to do a test. To make a long story short the used (for the first part of the testing) the arsenal pressure test guns, a standard M1 Garand and an 7.7 mm Arisaka rechambered/rebarreled to 30.06.
In the early parts of the testing they pressure tested the rounds prior to shooting them in the Garand and the Arisaka. They recorded the powder charge vs. the pressure.
They eventually got to high enough chamber pressures that they feared damage to their pressure test guns and stopped using them. With the previously recorded data for powder charge vs. chamber pressure they calculated the pressures after that point in the testing.
Eventually the Arisaka blew up. The M1 Garand kept going. They reached a load where the brass case itself failed and released gas/pressure back into the receiver/bolt. It blew the floor plate off the trigger housing, it bulged the bottom of the bolt, it busted the stock to hell and blew the small parts in the loading mechanism out with the floor plate.
They stopped testing and examined the rifle. The receiver, barrel, op rod and some other parts were considered serviceable and they put it back together with a new trigger housing and stock. The calculated chamber pressure that caused the cartridge case to rupture and damage the rifle was around 185,000 psi. After they replaced the broken parts they continued firing standard pressure 30.06 ammo in the rifle till they got tired of it and terminated the testing.
I don't try to get close to max. chamber pressure. I just load ammo that gives me the best groups I can shoot in my M1 Garands.
If I haven't recommended it before, Hatcher's Book of the Garand is a really good interesting book about the people and the development of the M1 Garand and many of it's competitors during the period between the world wars.
Garand started off as a tool maker. Not only did he design/develop the parts for the M1 he also designed/developed the tools to measure/test those parts.
Ever hear of the "sheep boards" or the "pig boards"? Those guys, in that time period were not the politically correct computer worshiping people of today. They wanted to know how different caliber bullets behaved at varying distances in flesh/bone. So they went out and bought a bunch of sheep, took them to a rifle range and tied them to stakes at varying distances and shot them with different calibers and bullet weights/shapes and then examined the bodies to determine which bullets performed best for penetration, tissue/bone damage, how quickly the bullet dropped the target, etc.
Someone pointed out to them that sheep were not a good test subject as pigs were closer related to humans in many ways (skin/bone/tissue). So they went out and bought a bunch of pigs and repeated the testing.
And no, the .30-06 FMJ rounds they used in those days was not the best. They chose not to use the best because they had millions of rounds of 30.06 in storage at that time.
Sorry for the long post. I could have left it at, "follow the reloading rules for M1 Garand ammo and you won't hurt it or wear it out."
