I have a dear friend who is a Military M-1 Garand and M-14, M-1 Carbine, and 1911 expert! He not only collects them but also builds and does regular work as well as custom match work on them. In fact, he use to build rifles for the states junior team and they won 7 out of 11 years at Camp Perry. So we have had several discussions pertaining to your question. According to him if there is a problem, with the M-1 Garand with hotter ammunition it possibly can effect the operation rod. He has advised me on many occasions, ammunition in the 2500-2550 feet per second range is probably best. Although he has fired hotter rounds without any noticeable problem depending upon the rifle. He advised basically it is conditional on the quality and the bends strength in the op rod. You can certainly control this with the amount of powder used related to presure as Robo has advised. He uses 4350 powder in his reloads. But if you want an M-1 Garand go for it! Nothing special other than the above. They are nice rifles if you get a good one! I have several myself. *But do not come down with a bad case of M-1 Thumb!!!!