ORIGINAL: SwampCollie
The performance of the WSM is nearly that of the WM, but, as you said the WM has a greater capacity. A quick search tells me the WSM has 80.4gr (water) and the WM 87.0gr (water). Thats quite a bit of difference isn't it? Why is it that the WSM is so close in performace to the WM when the capacity is (apparently) pretty drastically different? Is it just because the WSM is more effiecient? Something with the wider body of the shell or the like?
I wish I had an answer for ya swamp, but to be straight I don't know for sure.If one was to resize the shoulders on a WM to have water cap of 80.4gr, and taking away all factors like barrel dimensions or difference in barrels, I suppose the wider caseburnsmore efficient than the longer WM wildcat.
Some like eld might be able to chime in. I know there is alot of wildcatters on accurate reloading that could prossibly give the correct answer. But alot of people are going to tell you that the WSM is loaded to higher pressure limit than the WM.
There are loading programs out here like quickload, that one can play and model effects like this. But I am not a wildcatter, so I don't know.