Don't get in a hurry to do anything like this. It is wise to keep the ammo as close to original M2 ball spec as possible. The good news is that most of the common 150 grain under 2950 fps ammo is pretty darned close. The Springfield folks aren't dummies.
What WILL cause you problems OVER TIME is heavier bullets and/or slower "magnum" type powders that raise the pressure at the barrel end. This gives the op rod a "hammer blow" instead of a more desirable "gentle push".
There you go. The surplus is about 2700, most commercial is about 2900, which SA acknowledged. They only advise against heavier pills. My reading says the pressure curve is really the issue.