I am guessing that the Remington barrel shown was a particularly rough specimen. Remington invented the button rifling process. This type of rifling is generally known to produce smooth bores and clean rifling. It also work hardens the inside surface of the barrel making the the bore more resistant to erosion that the cut rifled barrels that were around when this process was developed by Mike Walker. Anything that I have read suggests that button rifled barrels generally win in 300-600 metre class contests. The cut rifled barrels do better at the more extreme ranges. Every barrel making system can produce diamonds, and sometimes they produce nothing more than a lump of coal.