A bit confusing title, maybe, but bear with me.

So I was looking through the Combat rules, checking up on the rule that states that you can exchange a damage die result with the amount of successes rolled. The rule states that if a weapon does several die's of damage, only one die is allowed to be exchanged. However, It doesn't specifily say how this applies to multiple hits.

Lets say I have a storm bolter and fire it on full auto. I have a base BS of 50, +20 for Full Auto, +10 for motion predictior, bringing it to 80. I roll a 07, making that 7 successes.

Now, I also get 8 hits (the opponent couldnt dodge any of them), each doing 1d10+5, with one Tearing die. My question is, can i switch out any damage roll that is less then 7, i.e, neither of the dies being 7 or more, with the amount of successes? Or can i do it for just one of the hits? Being able to do it o all of them seems kinda dangerous...

You just made the guy dance with a storm bolter. You dont think it might just be appropriate that oll that is left is bloody gobbets of flesh?

Replacing of each hit is not outrageous.

As I understand, you can exchange a single die of 1 of the hits with a 7. And as previous poster already said. I don't think that you will see the difference on the splattered corpse.

you will only the difference once in a while, if your player in a case of badk luck rolled very low on his damage rolls, juste enough to pass from " in dnager to die but still standing" to "splattered corpse".

Each hit gets to replace a die.

It makes no difference whether the hits were in a single round, or separate round. It's per hit. The rule refers to weapons that do two (or more) d10 with a hit, in that they can only replace one of those particular dice.

For example, a bolter rolls (essentially) 2d10 (b/c of tearing). Only one of those dice can be rerolled. an Ork Big Choppa, which does 2d10+tearing (= rolls 3d10), only one of those 3 dice results can be replaced.

If that Ork has Swift Attack and swings twice, however, each hit he makes gets to replace a value if needed, just like each was a single hit.