I've been reading that I should be using cast bullet data for plated bullets or backing off jacket data by 10%. Is this correct? I've been using jacketed data for my plated bullets in 45 ACP and have been fine. The reason I bring this up is because I want to be able to see what some of the higher velocities are like but I want to be safe. Mostly I'll be doing softer loads for target practice but want to know what I can do outside of that.

P.S. This is for 357 magnum loads

In my limited testing I have observed that plated bullets provide about a 10% reduction in velocity when compared to lead bullets of equal weight with the same powder charge. You really need a chronograph to determine what you are doing. At one time either Midway or one of the manufacturers posted some pressure tested data but that is no longer avilable on their websites. Experimentation is half the fun!

Berry's says to use jacketed data, but to stay below 1200 FPS. I think they are concerned about core separation. A speed limit like that favors heavier bullets to get maximum power factor and energy, since they can be pushed as fast as lighter bullets. At the other end, plated bullets will stick at low loading levels that that are useable with lead. It takes higher velocities to get accuracy with plated bullets than with soft lead bullets. I stuck a Rainier plated WC one inch from the end of a 6 inch M14 barrel. It was very difficult to get unstuck. I was using a light charge of WW231. TSquared's info about the 10% reduction in speed compared to lead is interesting. I don't have a crono, and have long wondered how much speed was lost. One problem with loading plated bullets is that there is very little published data specific to them. I shoot at an indoor range, which doesn't allow plain lead. They go over the ammo with a magnet. No steel either.

Rick

Check the manufacturers web-sites. One says use lead data, one says use jacketed data. They should know what their bullets do best at. Might find that medium lead/medium jacketed are the same.

When in doubt, ask the guy that make them...
If you want Chevy info don't ask a Ford guy.

...........is the title of an article in the September 2012 issue of Shooting Times. Lane Pearce compares plated bullet handloads for .357 mag and .45 ACP.

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-Bob