I loaded 4.0gr of N310 behind some campro (iirc) 230gr CMJ bullets, for .45acp. Less recoil than my 9mm. A puppy with that powder.....
So much so that I noticed on the last range trip with only a couple mags worth of ammo left, that at 15 yards or greater I could see the bullet flying through the air as I shot! I had to be looking basically within an inch of where it would hit the target, otherwise I wouldn't see it. But if I was looking almost exactly where the bullet hit (sounds easy hey? haha) I'd see the bullet's flight path! And I believe that was only .2gr below max.
I wouldn't risk using that powder with your magnums, not unless you're pushing a really light bullet.