I received these silicone grommets and am installing them in a silicone baking sheet for .308's (with GC) and .223's. To cut the baking sheets I tried using a wax cutter for .50 cal maxi balls but it proved too flimsy. So I have to wait till a leather punch arrives to punch out all of the .050" holes to mount the 1/4" thick grommets in.