Bulletmaker, I believe Mr Corbin has a formula/chart in one of his books, but it will only get you to the aproximate mix if jacket-lead that you will need. You will find that a guestimate will get you close, but a workout with a scales,micrometer, file and perhaps hacksaw is necessary. First, you make up 5 or 6 jackets about 1/4" longer than you think you'll need after you make your guestimate. (I hope you have one of the new adjustable length rounding over punches). Cut one of the jackets to the length you think is the "correct" length. Because you'll be reducing .5 tube to the .429 size, it's best to start your measuring before reduction... Keep good records. Go thru the process of making ONE bullet of the weight and design you want (you have to insure that the lead and jacket you use is the exact weight you want to end up with). If you have too much jacket reduce the length of your next 'test' jacket, and add a slight bit more lead to again equal what weight bullet you want. If, on the 1st try, you have too much lead, lengthen the jacket you use, and reduce the lead a bit. I've done this time and time again for several tube thicknesses in several different calibers. Once you 'discover' the correct jacket length , refer back to your notes as to how much you had to cut off of your test jacket to make that length, and adjust the lengths of your 'bullet tubes' and round over punch accordingly. Usualy, You will only have to make 3 or 4 test bullets before getting the right one. At this point, I suggest you contact Mr Butch Hairfield (see an earlier post he answered) and have him send you 10 1" long .429 .030"wall cups for testing. (Be sure your core seating punch is compatable as some tube is .032 or .035") Then, once you find the exact cup length you need using the above process (less the reduction of course), order a bucket of cups from him of that length. His product will probably be of less cost than the tube, and will certainly be less work overall. 8)
