I just got a 7-30 JDJ and the barrel is stamped 7-30 Waters but the 7-30 JDJ is on the lug. I have found the dimensions in the Cartridge Conversion book, but the barrel actually has room for the case to have a neck that is 1/4 inch long but the Case neck for the 7-30 JDJ is only .188. All the cases I got with the barrel have a .250 neck from the shoulder but the barrel has even more room for the neck. All the bullets I have just barely sit in the case and still only barely touch the rifling. Any suggestions or is this a re chambered barrel??