I guess the groove to groove diameter would need to be measured to determine the size...probably one in the .406-.408 range would do...but they're pretty big and heavy...wonder what kind of accuracy there would be in a 1" x 48" twist?arquebus said:Pretty sure Midway[url] http://www.midwayusa.com/ebro...323&categorystring=9315***652***675***9016***[/url] & Buffalo Arms[url] http://www.buffaloarms.com[/url] sell pre-cast & swaged bullets for .40 caliber BPCR. One of those might work for you.