I recently sold mine (completely "as issued"), but it was a pleasure to shoot CB's from it, particularly if they wore a gas check. Before you think about a mould, slug the bore and do a "pound cast " of the throat as you may be surprised at the dimensions and, ergo the mould you'll need. Once you do, check out NOE's offerings. Additionally, with that 1:7 twist, I never pushed my CB's fast: e.g., 9 - 10gr. Unique, or 14gr. WC 820 (AA #9). Btw, my rifle needed a .267" diameter CB and was very accurate with it.