Factory ammo is loaded to SAAMI specs. While the .30-06 and .45-70 to cite just two examples are loaded below what they could be due to old military rifles being about, most cartridges are loaded to the max especially the .25-06 which is factory loaded to 53,000 CUP which is magnum territory. Just try going hotter than factory for most cartridges and you'll have enlarged primer pockets and spent primers may even fall out. These are things that are actually occuring with the new, hotter Hornady Superformance ammo. And do you know if you have a tight bore on your rifle? If you do you will be acheiving higher velocities than normal and also higher pressures. If you load a rifle with a tight bore hotter than SAAMI you will risk a case rupture. If you've never experienced one of those believe me they are no fun.
The .30-06 is factory loaded to 50,000 CUP and it can be safely loaded to 52,000. But other than that most cartridges are factory loaded to the maximum safest pressures in all guns.