I have the exact same setup and both of my sons, 10 yrs old and 7 yrs old, have killed two birds a piece with it. Being able to reduce the LOP down to 10 3/4" with the retractable stock compared to the factory stock's 13 3/4" LOP has been a game-changer, particularly for my younger son.
Several of my friends have the same setup as well for their kids, and neither them nor myself have ever had an issue with the hammer.