Haha, I expected you to stab it, not try to shoot it in melee with a rifle. Technically only pistols can be fired when you're in close combat, but if the GM's rolling with it then I'm not complaining. That's three hits you get to roll damage for. Get some Righteous Furies!
You get 1d10+2 per every 2 DoS, up to a maximum of 3. You were firing at your BS +10, as you're not at point blank, but in melee unfortunately. Maybe you're point blank, as otherwise you wouldn't ordinarily be able to shoot? Either you're at BS +10, or BS +40. So if we're being conservative, you hit twice. You might have a third hit.
In other words- you hit multiple times due to it being full Auto. Each is a seperate hit, having it's attempt to get past DR and such totalled on it's own, but all happened the same round.
You're thinking of Weapon Expert. That talent grants you +1 Breach for every DoS instead of every 2 DoS. You've fully neutralized it, so your awesome Breaching powers aren't so useful. In total you're Weapons Breach + 2 + 1 per DoS, which is amazing for slicing through strong AT fields.