I started casting round balls for my flintlock about 1975, and bullets for my Ruger 357 handgun soon afterward. Over the years I have made bullets for a dozen or more rifle and pistol cartridges. I have designed bullets and had custom molds made. I considered most of my cast bullet loads successful and ever had a couple of rifles which regularly gave minute of angle accuracy with my cb loads. In other words, I thought I knew about cast bullets and handloading. However, I recently discovered that even after reading books and websites I never learned several important things.
There must be many cast bullet shooters who, like me, have absolutely no technical or scientific background. I never even took a course in mechanical drawing. Those of you who understand such things often assume non-technical readers can talk your language, but often we only half understand you. It is possible to make rather accurate loads for modern rifles without knowing much more than the basics, but antique rifles pose other problems.
For example, my experience is that most modern guns have a grove dia set by SAAMI specs and the advice from the Lyman Cast Bullet Handbook to "slug your barrel" isn't usually needed. Most .30 cal rifles have a groove dia of .308". Cast bullet shooters found years ago that bullets .001"-.003" over grove dia usually work well. When we slug a modern .30 cal barrel we know what the slug should measure, and we often look at the scale on the mic and see what we expected to see. Variations in groove dia are within the .001"-.003" acceptable range, so even inaccurate measurements are within tolerance.
I recently bought a 1893 Marlin levergun in cal 32-40. Handloads with .321" dia cast bullets and factory ammo showed keyholes at 50 yds. I dusted off the dial caliper and measured a slug--.330" I measured. Before spending money on a custom mold and sizer die I used a micrometer to measure another slug. .326" This discrepancy led me to a couple of days trying to learn some of the things machinists and other technically trained people know, but which I'll bet many other handloaders do not.
I'm not going to teach a course, but I hope this is useful to some of you.
1. The internet. Many of you are too old to be really proficient with the net. I used the computer to check on a few internet gun forums and to order stuff from Midway. I have discovered that there are dozens of websites and videos a cast bullet shooter may want to see, including all sorts of amiture gunsmithing instructions. Just Google a topic or question and there probably is something useful. Including:
2. Caliper or micrometer. There are many machinists forums and sites, and a brief query obvipusproduced an explanation of why the mic is usually more accurate and repeatable, as well as instructions on how to use both of them. Incorrect use is bound to produce inaccurate measurements, and of course, I have been using them wrong for years.
3. Precision hole dia. Bullet sizer dies are made by Lyman, Lee, and Saeco in common sizes, but what do you do if no one makes one the size you need? I want one .326" and the obvious way to do this is to get a .325" die from Lyman (about $30 from midway)and enlarge the hole. A drill bit is not going to work, but if you go to the McMaster-Carr website you will find hundreds of reamers, hones, burrs, and other tools to produce holes that are polished and precise. Instructions on when and how to use them. I have not done this yet but I have ordered taps, dies, and other machinist tools from them. Reasonably priced, fast service, and much wider selection than Browells..
4. NOE Molds. The owner is a shooter who makes custom molds to your specs. He also sells a bullet sizing die much like the Lee lube-sizer (about $20) but with interchangeable inserts for a wide range of bullet dia. I just ordered one for the .326" dia for about $70, but if I want other sizes I can get them for less than $10 each. Since neither Lee or Lyman makes a .326 sizer die, this looks like a good deal. Inside neck expanders for the Lee flaring tool for $6.50 each.
This is too long, and many of you know all of it, but I hope its is useful for others who cannot take a gunsmithing course. If David wants to delete it, that's ok by me.