Will it bend the op-rod on my 7.62x51 Garand if I shoot American Eagle in it?
Depends on the bullet weight...
The Garand gas system is setup for a 147gr bullet exiting the barrel at around 2700FPS.
If you use a heavier bullet gas pressures increase. Supposedly (all I shoot is 147 grainers so I don't know from experience) trouble starts at around the 165/168 gr range and can bend the op rod.
I believe that there are now adjustable gas tube plugs you can get for the Garand like the ones available for the M1A which makes it so you can shoot heavier bullets out of a Garand.