I have come to prefer the polished well carded look on a browned or blued barrel. And for that, you must draw file, and polish with abrasives to at least 400 grit.
Op, your file is pinning....holding on to little pieces of steel that stick in the teeth and on the next stroke, leave a lengthwise scratch. These will need to be filed out. Abrasives are just too slow.
My draw filing file is a 22" single cut mill bastard. I've had it since the mid 80's and have drawfiled over three hundred barrels with it, and it is still working well. When I'm done filing a barrel, the ball of shavings that result look like steel wool. I discard these carefully because an errant spark will ignite this ball and become a red hot glowing ball of disaster in your shop.