I don’t have a .38 LC revolver, but I collect things, and I’ve got some .38 LC brass that I’d like to load up and shoot in my Taurus .38 Special +P revolver and S&W Model 19 in .357. Hodgdon has load data for 125 gr and 150 gr lead bullets, and I’ve loaded the 125’s in the past, but I’ve not been able to find .358” 150 gr bullets. I’ve been thinking about the possibility of using 158 gr cast SWC bullets instead.
Apparently no data exists (or I can’t find any) for 158 gr. In other cartridges I’ve used bullets that were close in the past, but they were usually 2 or 3 grains different; not 8 grains. Here’s the info that I’ve come up with, but I can’t verify any of it.
1. 38 Long Colt has a max pressure of either 12,000 PSI of 12,000 CUP. There seems to be some debate on this.
2. According to Lee #1 and some older Vihtavuori manuals, a 10% increase in bullet weight causes an 8% increase in pressure, and 4% reduction in velocity.
3. Hodgdon has load data for 150 gr bullets of up to 777 FPS.
If this holds true, and if Hodgdon max load data produces the maximum allowable pressure, 3.3 grains of HP-38 with a 158 gr SWC instead of 150 gr will yield about 12,500 PSI/CUP (depending on which units are correct), and a velocity of about 760 FPS in the same length barrel.
Has anyone ever shot 158 gr bullets from a .38 LC, and if so, do my numbers seem to “add up”?