This bullet was designed by legendary IHMSA shooter David Bradshaw and his friend Lee Martin. It was designed specifically for moderate loads in the Ruger 357 maximum. David and Lee have tested this bullet out to 200 yards with good results, as discussed at SingleActions.com.
At this point I'm not listing it as one of my "Proven Designs" because I have very high standards for those proven designs -- I haven't even listed my personal 35 caliber revolver bullets yet, because my testing is not complete. But you can certainly order the Bradshaw-Martin design by printing it out and mailing it in, or simply ask for the Bradshaw-Martin design and I'll know what you are talking about.
Here is the design exactly as Lee originally specified it:
Or if you prefer to use clip-on wheelweight alloy, which bumps the weight up to 195 grains.
FYI David and Lee have been pushing this bullet 1400 - 1450 fps with 17.0 - 18.5 gr. IMR4227. The latter fills up the powder space but is still well below maximum pressure, perhaps around 35 ksi if you believe Quickload.