See the FAQs, there are several links to home crowning with no special tools requires, as long as the crown is recessed slightly, doesn't matter too much, cut it off, file it smooth and square, use a carriage bolt and valve grinding compound to recess the crown, done it several times myself. Have also use a crowning tool, not a lot of difference in the finished product cuz they all shoot good.
IIRC, Gendoc or LONGTOM has a rifle with the muzzle cut at an angle that shoots bug holes!

Tim