Just my 2 cents. I posted in another thread that i had nothing but problems practice shooting and sighting in with muzzys. The heads I was usind were ones that had been shot many times, at targets and thru deer. After careful inspection I found that some had either bent ferrules or bent blades. Check blades very carefully after being shot into any target, especially if you are using helical. The force of the spin on impact will bend the blades and then that head will not fly true. Spin test to check for wobble and bent ferrules, as this will also drive you mad when sighting this bh in.