I purchased a 22WMR barrel for my Sako Quad Varmint just over a month ago and now I am using it a lot more than my 22LR. I have seen loads of questions online about what barrel length works with the magnum so thought I'd pop this up on the www.
The standard is 22" plus mod and in the Varmint version (heavy barrel) it was such a pain to carry around, point out of a car window and a little too heavy to do free standing shots on those close range bunnies I sent it in for a haircut at my local RFD (R&B Sporting Ross-on-Wye). I dropped it off to them on the Wednesday and they had it back to me the following Monday, high quality work for a good price. It came back at 14.5" and would still do a thumbnail size grouping with my addict hands at 100 yards. I tested the barrel before it was sent away at this range just to see if there was any loss in accuracy and I can safely say on mine it stills shoots as great.
Below are a few pictures so you can see the grouping and a shot of the rifle in Walnut my 22LR barrel is the same length as well and it still shoots spot on!