I remember reading several Threads and post in the past on 22 lr saying it is not wise to use 22lr rounds that are less than 1250 Feet per Second in certain guns. Referring to the design of the barrel lining I learned not to use uncoated lead 22lr rounds in certain guns that I may or may not own. I also learned the hard way why Thunderbolts are hated. However I also learned how to remove extreme lead when I used thunderbolts.