I currently load 158 grain lead SWC bullets but extreme bullets has 158 grain copper plated bullets with a lead core. They usually offer free shipping so I'm thinking of trying them out. I'm happy with the 3.4 grains of HP38 I use under the lead bullets. Would the copper plated bullet use the same recipe?

I switched from lead 148 gr. DEWC to Xtreme 148 Gr. plated DEWC ... I was using 2.8 gr. Bullseye for lead, bumped it to 3.0 gr. Bullesye for the plated. Very happy with the Xtreme bullets.

It MAY but I have cautioned others in the past against using "typical" methods of load development with plated bullets-- especially in revolvers. Here are the main points I want to make:

A plated slug is FAR more difficult to push down a bore than any lead bullet and revolvers are particularly problematic because of the cylinder gap.

Typical development has us starting low and "safe" and working upward. With plated, you run the very genuine risk of sticking a bullet in the bore when you run too "safe" and more so in a revolver because the much-needed pressure can (and WILL) leak out of the cylinder gap.

I keep detailed records and I have quite literally sent tens of thousands of plated handgun slugs down range. Of those, I have stuck three of them, all revolvers, all .38, all loading TOO conservatively.

No, plated is not jacketed. In my experience however, it's a LOT more like jacketed and nothing like lead.

For plated, I start with a FIRM load and carefully drop the load a bit rather than the typical development in the other direction.