700X or 38 and 357

I have reloaded 45 ACP using my own cast (WW) 230gr RN bullets and 4.8gr of 700X. The results were acceptable. I am now setting up to reload 38 and 357 using cast 158gr bullets and would like to use 700X for them as well. I will be using them in a Smith combat magnum 357 in excellent condition. I have both 38 and 357 brass but do not want to put the heavier load in the 38 brass because of obvious problems if someone were to try to shoot it in a 38. I have found recommendations for loads that were all over the map, from 3gr to 4gr for the 38 and from 4.2gr to 5.6gr for the 357. Does anyone here have recommendations (and experience) for the use of 700X using similar or the same components and revolver as I propose? I know there are better powders for this application but 700X is what I have on hand. Thanks.
 
Since 700x is a very fast powder, the volume inside the case after the bullet is seated will make a HUGE difference in peak pressure. This is likely why the loads are "all over the map".

When you use a published load that is near/at max, be careful that the OAL AND bullet lengths are the same as what you have. If your bullet is longer and you seat to same OAL, then interior volume will be less and your peak pressure will be much higher. (but it won't change velocity very much)

700X is a very good powder for lighter loads in 38sp.
 
For 38 special, I load 3.7 grains 700X under a 158 grain LSWC Keith design commercial cast bullet. Gets about 800 fps average out of 6 inch 686.

I also load 38 +P+ (that's what I call them) using 4.3 grns 700X and my home cast Lee TL design 158 grain SWC. Gets 990 fps average out of 6 inch 686.


I do not load full 357 mag with 700x. Too fast. If you want to load down a 357 case, try 4.5 grains 700X under 158 grain LSWC. Should give you more than 1,000 fps out of 6 inch barrel.
 
Thanks

My smith has a 4 inch barrel so I won't get the same velocities but I am using the Lee bullets and will also use your recommendations for powder weights. Incidentally I have used 4.8gr of 700x in my 45acp with good results, seems to simulate UMC recoil pretty well, but I haven't chronographed that load.
 
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