Just got back from our Texas hill country hunt. While my daughter was not quite ready to shoot the deer rifle, she did shoot a racoon with a .22, her first kill. It dropped when she shot it, but when we went to look for it, could not find it. She was very disapointed, but as we looked around, a coon started coming down out of a tree, and I was not going to let my little girl's first kill get away. All I had was the 300-221, and in its first test, I can say that it will kill a 5 pound racoon effectively. In any case, she and I were very proud of her first kill.
The next evening we were in a blind and got to try the round on a deer. A little buck was standing about 80 yards away almost facing us. It dropped in its tracks and never took a step. The bullet had torn through the heart and ended up in the guts. Up to that point I had been carrying my '06 with me in case I saw something big, but was impressed enough that the next morning I left it at the camp and only took the 300-221. Of course, even though I had not seen one so far, an axis buck came out to the feeder. I had a good broadside shot at about 80 yds, held mid chest just back of the shoulder and hoped. THe buck dropped in its tracks, kicked a couple of times, never got up. It weighed 180 lbs, and the bullet had gone through one lung, hit the spine, through the other lung and one tiny fragment lodged under the skin on the other side. The next evening, our last hunt, I shot a spike with it again at about the same distance, and again the buck dropped in its tracks. Again, both lungs and the spine, with an exit wound of about the sized of a half dollar. In all three cases, no wasted meat.
I had built this rifle for my little girl, but I had so much fun with this that I may have to build her her own. Someone mentionned the weight of the AR 15, but I carry the guns to the blind and my daughter shoots sitting on my lap resting the rifle on the stand window, and the extra weight will also help with the recoil. There is also the advantage of the collapsible stock adjusting to her size. I am still curious how the round will do without a hit on the spine, ie if it will leave a good enough blood trail. That said, I also have to say that in a contender I would probably shoot the 7TCU, but I will start my girl with the AR in 300-221 because of the reduced recoil. Regarding the brass, forming it from .221 fireball is no harder than forming the TCU from .223.