I would not be afraid to buy any H&R/NEF gun,any of the ones I have shot have been tack drivers and a good deal for the money. A bull Barrel is a heavier barrel than a standard barrel used for target/varmint/tactical shooting that due to the heavier barrel is stiffer aiding accuracy. Button rifleing is a plug forced down the barrel cutting all the grooves at once and is a common form of rifling. Jim