From a recent issue of Handloader, the powder companies finally admitted that HP-38 is the same as W231.
Something that I find humorous, as I have a Ken Water’s article from Handloader, where he “gave up” on W231, but ballyhooed HP-38.
Even though powder companies blend the powders we use, I understand they only blend to a tolerance of 10%. You would expect different lots to give different peak pressures.
Also, smokeless propellants have an exponential slope to their burn curve. Which means that the burn rate increases incredibly fast.
A tenth of a grain difference don’t mean nothing, considering all the tolerances you have to the various articles under test.
Here is my W231 data. I am happy with a load that is just about 800 fps with a 230. My 230 FMJ GI 2nd’s function the pistols and shoot just fine.
Colt M1911 Stainless,
230 FMJ GI 5.5 grs W231 Mixed Military WLP
9-Oct-05
1.265" OAL T = 64 °F
Ave Vel = 792.4
Std Dev = 15.87
ES 70.15
High 825.5
Low 754.9
N = 24
Kimber Custom Classic
230 FMJ (GI) 5.5 grs W231 Mixed Brass WLP
18-Mar-07 T = 62 °F OAL 1.265" taper crimp .469"
Ave Vel = 780.5
Std Dev = 14.17
ES = 51.66
High = 798.7
Low = 747
N = 23
