It's always best to compare firearms with real info. A 3" SP101, KSP-331X, 27 oz, & MSRP $607 isn't
that much larger than the S&W 3" 60, #162430, 24.5 oz, & MSRP $853. They use the same 5-shot speedloaders, too. Both started life as .38's, as well. Now the construction method... the Ruger is cast steel; the S&W is hammer-forged and hardened. The S&W has a fully adjustable rear sight, the Ruger is fixed. The only SP101 with an adjustable sight available now, and it's windage-only, is the .327 Federal model. I've owned - and worked on - many Rugers, but my SP101, a 4" .32 H&RM, was the absolute worst QC new firearm I have ever seen, much less owned.
The best choice nowadays for a pocket gun, IMHO, is the S&W 442/642 hammerless .38 Spcl +P. New, they had a $50 rebate - and I heard S&W has lowered many prices recently, too. Believe me, a 158gr LHPSWC +P round fired from a 642 is sufficient for protection - and a decent 'bounce' in the hand. I've shot a 340 - the older 12 oz model with the Ti cylinder - with some hot .357M CorBons - and it is the last thing I'd ever want as a PD firearm. Too much recoil - no mass - and nothing to hold on to. If you miss with the first shot, you might have to search for the gun!
The choice I made for a HD firearm was a bit extravagant - a S&W 2 5/8" PC627 UDR, an 8-shot .357M (See below.). I had the money from the sale of an old friend. Of course, it has gone down from $1,185 to $1,049 MSRP lately - my luck. Note the moonclip full of Remington R38S12 .38 Spcl +P 158gr LHPSWC's - my choice for protection. I reload - so I make plenty of .357M plinkers - wimpy - my choice.
Now - the K-frame has a small forcing cone edge - thickened in the larger width L-frame's front strap. Either will shoot standard 140-158 gr .357M's fine - the thin fc of the K-frame can erode and crack with continued use of 110-125gr hyper hot .357M's. They never established when - some say <10k, some say 40k rounds - of those lite weight hot loads. As snubnose K-frames are only available on the second hand market nowadays, the shooting history of a used one is a crapshoot. Still - a barrel will fix it - and S&W still has plenty of SS and blued barrels.
I bought a pair of L-frame .44 Specials, 296 & 696, new on the same day eight years ago - without considering their fc's. Oops! Another dimunitive fc, barely made possible by the thicker front strap of the L-frame. Still, .44 Spcl is a low pressure round - and only minor flame cutting has been noted on the topstrap over the b/c gap - and only in the alloy 296 AirLite Ti. BTW, that Ti cylinder, as delivered with the first 396's, is too tempermental for me - no short cased, ie, .44 Russian, rounds for it, according to S&W. They dropped the Ti cylinder in general - and from the 396 in the last 'Night Guard' variant, thus it's last 24.2 oz weight (The original was 18.0 oz.). It would be fine with .44 Russians or Specials.
A very S&W-opinionated Stainz