The 45cal pellets are smaller than the 50cal pellets . They are safe to use but you better site in with them though to see how they shoot your 50cal projectile . The 45 and 50 cal are both 50 grain pellets , but the projectile will not be seated in the same spot in the barrel because the 45's would be longer and thinner than the 50cal pellets . Probably not that much difference but you need to site in with them and see how they do .
Cant you bring them back and get the right ones ?