When Curtie is talking to Mae, he pulls out a bag of .50 caliber rifle bullets and starts sharpening the tips of them with a file. While that looks very sinister, it is something a serious shooter would never do. A hand filed tip on a bullet could dramatically alter the flight path and make it highly inaccurate. A filed down bullet would also have a negative impact on the air pressure over the projectile and would compromise the expansion and/or overall penetration. It looked very cool, but a pro would never do that.