Meplat
The flat or open diameter at the very tip of a bullet, whose size and uniformity influence the round's ballistic coefficient.
The meplat is the small flat or open hole at the extreme nose of a bullet, the point where the curved ogive is truncated rather than coming to a perfect point. Because no jacketed bullet drawn from a forming die ends in a true sharp point, every bullet has some meplat, and its size affects how cleanly air separates from the nose. A smaller, more uniform meplat generally lowers drag and raises the ballistic coefficient.
Meplat consistency varies from bullet to bullet within a box, especially on open-tip hollow point match designs where the jacket is folded over an open tip. Serious long-range shooters sometimes trim and point bullet tips to make the meplats uniform, which tightens the spread in drag and helps drops stay predictable at distance.