Well, a DicePool of 10 for shooting stuff is easy enough.
You just need in good physical shape(quickness 4) and a professional shooter (shooting stuff skill 4).
Then get a Smartlink(2) and you are done. Of course, there are also adverse situations where you lose pool dice again . .
There's ways to get your shooting stuff Dice Pool up to . . 30? i think . . in character generation to boot . .
Thus, they saw fit to introduce a rule that caps dice pool at either Attribute+Skill x 2 or at Attribute or Skill x3, which ever is higher . .
Because one of the first claims made when they chose the new System for SR4 was that they wanted to lower the ammount of dice people needed to roll . .
Appearantly, the ammount of dice rolled was waayy too high in SR3. Conversely, the only time when i have seen 15+ dice being rolled on a regular basis was for Adepts with skill 6, improved skill 6 and combat pool 6 or Trolls/Orks with augmented STR doing something that was based on the Attribute rather than the skill(seldom) or Orks/Trolls with augmented Body shrugging off damage . .
Because under SR3, getting your Body up to 15 was trivial for both Orks and Trolls . .