Full length re-sizing a couple times won't make the case head split, I full length size every time. Take that rifle to a gunsmith and have the headspace checked. It is possible that what is happening is you have a bit to much. When the fireing pin hits the primer, the case is mover slightly to far forward and on firing, the case is grabbed up front and has to expand backwards. If you watch your fired cases, you should notice a bright ring form around the case head if that is happening. Don't know if a gunsmith can fix it in a break action but I would think the manufacturer would. Friend of mine had the same thing happen in an H&R Topper (same rifle) in 22 Hornet, his was also headspace. He just reduced the loads by making a cast bullet gun out of it.