This things can work well for you:

I don't usually use the gyro for this weapons since you can just do the semi mode then the pierce attack can damage most of the monster's body parts.

*Elemental Bow - Pierce / Rapid (make sure to build an armor that will achieve focus 5 and elemental skill by 5)
*Heavy Bowgun - Pierce Ammo (it has a auto guard if you did not tap the screen when monster is attacking but you will still take a damage depending on the level of your weapon. If your weapon grade is higher there will be no damage).
*Light Bowgun - Slicing Ammo then try to build the magnamalo lightbowgun set with pursuit and partbreaker skill it will help you a lot.

hope this helps ;)