I'm new to the forum so forgive me if this question has already been answered. Does anyone know if a list exist that denotes what serial number prefixes pertain to available calibers. My 13 year old son has hunted with an NEF .243/muzzle loader for three years. He has taken two does and one six point (3X3) buck with it. Upon returning from Iraq two weeks ago I decided that I would get one for myself. I set out to obtain one in 25-06 but learned that there are currently none available, atleast here in NW Florida. Yesterday while attending a gun show in Pensacola I thought I had found my gem. I purchased a NEF rifle in .223 with a beautiful laminated stock. I called H&R1871 this a.m. to see if I could purchase a 25-06, 7mm-08, or .270. To my dismay however, I learned that the only barrels available for my "gem" with a serial designator that begins with NF are the 45-70, 30-30 44mag, 357mag, and the 22 Hornet. While these are great calibers they are not what I'm looking for. HELP!!!