I have both and shoot both. For whatever reason (long time familiarity most likely) I shoot the K Frame S&W M66-8 2.75" .357 Mag better. Here are some chrono results from my then new Labradar test run.
Labradar Muzzle Velocity (familiarization run)
60 Deg F
S&W M66-8 2.75" .357 Mag
130gr Fed Hydra-Shok JHP "Personal Defense" PD357HS2 H …….. 1,416 fps avg (84 fps ES) -- two rounds
140gr Underwood Xtreme Penetrator (Philips head mono metal).. 1,422 fps avg ( 5 fps ES) -- two rounds
158gr Horn Xtp - 15.0gr A2400 Std small pistol, new Starline...… 1,316 fps avg (49 fps ES) -- six rounds
165gr CSWCGC (358156) - 13.0gr A2400 New Starline ...… 1,180 fps avg (84 fps ES) -- six rounds
180gr Buff Bore …………………………………………………………………………….. 1,312 fps avg ( 6 fps ES) -- two rounds
185gr LFNGC (Beartooth), 15.0gr Lil'Gun, CCI 400 New Starline.. 1,228 fps avg (14 fps ES) – two rounds
200gr WLNGC (leadheads), 13.4gr H110, Fed 205, New Starline.. 1,102 fps avg ( 4 fps ES) – two rounds
200gr WLNGC (leadheads), 14.4gr H110, Fed 205, New Starline.. 1,155 fps avg ( 2 fps ES) – two rounds
(purported to be the “Doubletap” load info)
200gr WLNGC (leadheads) handload with Lil Gun ………………………. 1,266 fps avg ( 2 fps ES) -- two rounds
Load data not given -- maybe too much of a good thing. Spent cases fell from chambers, and no obvious signs of over pressure. Recoil was heavy for a .357.
If even needed, I would limit useage of the 180, 185, and 200gr loads in J & K Frame guns
Also ran two Buff Bore 180s thru 16" Rossi M92 carbine ……………. 1,894 fps avg ( 6 fps ES) -- two rounds
When I first reloaded for my M&P40, 4", I found that Hodgdon's Longshot load data gave me 1370fps average for a Hi Tek coated 18bhn 155gr lswc. The M&P has full casehead support, and I stretched my COL out to 1.16", so no worries there but it would throw my brass into the next county. I throttled it way back to almost the starting load to arrive at 1250fps which seemed reasonable. I also fiddled with 180gr fodder and quickly decided to stay under 1200fps.
Turns out that lots of folks discovered the same thing with Longshot - the 40sw becomes the 10mm lite.
I still carry a revolver when I'm serious about bears, ( 329pd with 270gr WFN @1150fps), but my knife is a Havalon Piranta and I don't have any animal skins.
