I did have a chance to chrono some of the 4756 loads:

Using a 175 grain 358429 and 4756/8.0 grains with a Winchester SP primer from a 6" GP-100 gave 1185 fps. This was with the bullet crimped in the crimp groove for a 1.655" LOA.

Using a Hornady/Speer/S&W swaged 158 grain SWC-HP with 4756/6.8 grains and a Winchester SP Primer gave 1055 fps from a 7.5" Blackhawk. The LOA was 1.600"

Using the same combination as above but with 7.7 grains of 4756 gave 1200 fps.

One last comment, the last two loads, when using the Speer or S&W SWC-HPs, are wonderfully efficient killers of small game. They are not too loud and critters just topple over when hit. The S&Ws are no longer available and haven't been for a long time, but I have a lot of them loaded up from days past.

Edited to correct an oversight - all of the above loads were put up in .357 cases.

Hope this helps.