Antler lockups happen when two bucks square off and battle for supremecy. It occurs quite often and usually results in death for but sometimes just for one.
Check out these photos from the Palmer Course at La Cantera near San Antonio, Texas. The superintendent had an unusual surprise waiting for him one recent morning.
Likewise, check out all the unusual lockups by clicking the category at left. There is an unusual post of Elk being locked, of one buck surviving while his opponent is eaten by other critters and even a post showing a rancher dislodging two tangled up bucks by shooting off one of the antlers. Good stuff.