My oldest daughter who just turned 10 at the beginning of the month shot her deer during the opening morning of the Minnesota youth rifle season. She used her custom 223 Rem that I built for her and made a perfect shot dropping the doe on the spot with a 65gr Sierra Gameking.
The deer was quartering to us and the bullet broke the top of the shoulder and hit the spine ending up on the off side in the back strap. The shot was 107 yards and I was surprised how well that 223 performed. I had some reservations about using it but she shoots the rifle well and I did not want to induce any issues trying to make her use a bigger rifle that she was not comfortable with.

The deer was quartering to us and the bullet broke the top of the shoulder and hit the spine ending up on the off side in the back strap. The shot was 107 yards and I was surprised how well that 223 performed. I had some reservations about using it but she shoots the rifle well and I did not want to induce any issues trying to make her use a bigger rifle that she was not comfortable with.
