This is a new caliber for me. Any suggestions for preferred powders, esp. with 140 grain bullets?
Brice

IMR7828SSC
H4831SC
Retumbo
Rel 19
Rel 22
All worth a look.

muck

Here in upstate NY I'm content with 130 gr bullets at 3000 fps and I load my 270WSM with XMR4350 or IMR4831. You can find 140 gr bullet loads here:
http://data.hodgdon.com/cartridge_load.asp

Firstly, I only use 150 gr. bullets in my .270 WSM so...
The powder I finally settled on is Retumbo. IMR-7828 SSC would perhaps be my second choice. Both of those produced velocities close to that listed in the manuals when used as recommended.
For me, none of the Reloader line including RL-25 produced near the advertised velocities.
Have not tried H-4831.
Good luck.
Bear in Fairbanks

I run H4831SC under a 140 grn Accubond in my 270 WSM

I shoot four rifles in .270 WSM and consider it one of the most useful rounds offered today. My powders of choice for 130 gr. bullets is RL-22, 140 gr. bullets RL-25 and 160 gr. bullets Magpro. My rifles will not shoot the 150 grainers as well as those mentioned. I have shot hundreds of rounds with the these rifles at targets preparing for hunts for Deer up to and including Elk. Good shooting.

I have been using RL 22 with 140gr Accubonds with excellent accuracy.

RL-25 works really well too. Any of the slower than 4831 powders will work.

My first .270 WSM worked well with 130 gr bullets and IMR-4350 for mild loads and Reloder 19 for warm loads. For the 140 gr bullets, my rifle's favorite was Vihta Vuori N-165 and the Nosler Accubond, with Reloder 22 close behind. My new Model 70 Ultimate Shadow seems to prefer 150 gr Nosler Ballistic Tips which I currently load with Accurate Data 86 Extruded powder (a surplus version of the old Accurate 3100). I plan on trying some Reloder 22 and 25, as well as Magpro to see if I can improve the accuracy and velocity with the 150 gr bullets.

According to Hodgdon, W780 was the powder that was designed for the WSMs. I bought one (an R1) for the wood and fought with it 2 months before finding a load with 140 gr NABs and 780 that would hold 3 in 1" @ 100. It did nothing a regular 270 would not and didn't make much sense in a R1 which is a long action. Finally found a plain wood R1 in 300 WinMag, swapped the wood and sold the 270. The 300 shoots a 25 gr heavier bullet just as fast and just as accurate.

Just FYI I also tried W760, Big Game, H & IMR 4350,4831,4064.

Good luck !

Thank you for the comments, gentlemen. Likely saved me some powder, shot and time.
Brice