1.) When Star produced powder slides they would drill a certain size hole then use a Taper Pin Reamer to enlarge the hole to get the desired charge. So, all of the holes are tapered. Usually the large end is at the top of the slide, sometimes its on the bottom. Your hole measurements have to take this into account.
2.) It was common practice for users to modify powder slides to get the charge they wanted. Sometimes its obvioius that it's been modified, sometimes not, so you can never really trust the charge weight marked on the slide.
3.) In my experiance, Bullseye powder slides always throw 0.2-0.4 grains more than marked. This might be due to lot variation, but I think the powder has changed over the years.
4.) All powders vary lot to lot. The manufactures say up to 16%, though I have not found the variation to be that great. Typically you can expect a +/- 0.1 grain variation from lot to lot. So you really do have to manually check your charges periodically.
5.) What we produce now, in all four sizes (0, 00, 1/2" & 5/8") are powder slides that use interchangeable bushings and we custom make bushing for the charge of your choice. We use the published density for each powder (VMD) to calculate the hole size, so keep #4 in mind.
