What was the range you were shooting at? How many rounds fired just prior to the bump? Was it perfectly zeroed? How many rounds fired after to verify the shift? Is it a BR or NXS? What rings and bases are on it now? Have the bases or ring come loose? Action screws are tight? Has the reticle or scope rotated? Has the scope moved forward? What cartridge the rifle shoots? How much does it weigh? Was the shift vertical or horizontal? Have you shot it since and rezeroed it? Does it hold a zero now? What's the history on the load you're using, is it a new one?