If its not the shooter, you might try a different bullet as well. These smokepoles can be pretty finicky. Keep at it, you'll find a combo that groups well. keep in mind, the odds of the Winchester liking the same load as your XR is pretty slim. Another option is to sell the Winchester and get your son an XR. I have one as well and absolutely love the thing, get 1.5" groups with 90gr of 777 ffg and a 300gr Hornady SST. Just my

, take it for what its worth.