I shoot flat based conicals that I make out of a LEE bullet mold. They are 300 grain in .54 caliber. I have tried it both ways. With and without the bore buttons. I make sure I lube them heavy with Bore Butter and I really did not notice the difference in accuracy out to 50 yards. I have never shot them to test their speed both ways. This is something I would be interested in, but I do not have the equipment to do this...