Keep in mind, the predecessor, .32 H&RM, was around since 1984 - and everyone but Charter Arms (.32M Undercoverette) had dropped them as of last year due to poor sales. Reportedly, Ruger had a glut of the 3" SP101 in .32 H&RM last year - then out comes the '.327 Magnum', which, oddly, would only require rereaming the chambers deeper - and restamping the caliber - voila, .327 Magnum SP101!
I had a 4" .32H&RM SP101 until early in the summer. It has a cheesy windage-only adjustable rear sight. The chambers - like my 4.6" BHG SSM - measured .337+", barely in SAAMI specs. Since my Dillon dies sized my Starline brass to the same .334" as commercial brass, both would bulge slightly - even weak .32 S&WL MagTech lead - in the chambers, making extraction much more difficult - and 'working' the brass, reducing it's reloadable life. My local pusher had to return the next to the last one he got in, just weeks ago - it spit too much - timing/oversized chambers suspected. The last one had obvious chamber problems - never sat in the display case - went back last week.
I left the .32 H&RM/S&WL world because ammo & reloading supplies were getting hard to find and as expensive as .38 Special. I'd rather launch the .38 Special - I have a lot nicer firearms to launch them in than an SP101. YMMV.
Stainz
PS The GA Arms 100gr (XTP) JHP in .32 H&RM was chrono-ed from my 4" SP101 at 1,186 fps - pretty hot - and nasty (spit!).