Marshall/Sanow is a big can of worms on most gun sites. I agree, the stats are better than shooting goats, jello, etc, and I tend to reference the M/S data when comparing load results. I don't live by 'em, but I figure if a load breaks 70 percent in their data, it's worth carrying and if it breaks 80 percent it's a good load.
However, far more important than how high in M/S stats a load ranks is how accurate and shootable it is in the gun and in the case of autos, how reliable it is. So long as the load ranks over 70 percent in the M/S data, preferably 80, and it's accurate an reliable, hey, go for it. But, obviously my handloads aren't on the street, no stats for 'em. But, if they perform over the chrony similar or better than M/S ranked loads, I'm good with it.
I don't know if there's a .357 load that ain't decent, tell ya the truth. I shy from the heavy stuff, too much penetration for self defense uses, but tend to go with 158 or less JHPs. I'm pretty confident that a 140 grain JHP Speer bullet at 1335 fps will do the job in my little SP101 and it's not bad on recoil, though it has a helluva flash/bang. The 125 grain stuff just doesn't live up to expectations in the little gun. I could go with a faster burn powder, but the 140 performs so well, I ain't worried about it.
About the ONLY thing M/S data really proves to me is that .22, .25, and .32 ain't for me and .380 is really marginal. And, no FMJs in 9 or .45 for me. Beyond that, any service caliber has loads that I'll carry and be confident in. I really don't understand a lot of the caliber war stuff other than the big and slow guys. They have to justify the 1911 even if they have to make up "science" for their big/slow bullets. They have to show that a wonder nine is a pip squeak not to be relied upon so they can argue against a gun with twice the firepower in an equal size or smaller gun. That's where 90 percent of the arguments including the M/S data trashing comes from, the 1911 fanatics. They have invented some REALLY hilarious formulae and pseudo-science to support their caliber/platform above any and all others. When men are carrying phazers in the 24th century, they'll still be justifying their .45s. No death ray can equal a big bullet, ya know, and God's second son, JMB, invented the 1911 after all. You can't argue with God. :
