Ruger's web-site lists three SS Ruger Single 7's chambered in 327 MAG - with barrel lengths of 4.63" - 5.5" - 7.5".
All three models are listed as Lipsey's Distributer Exclusives.
I have, and have had, Ruger Single Action revolvers in various grip and frame configurations and sizes - in calibers ranging from 17 HMR to 44 MAG.
I find the Ruger Single Action revolver that has the most comfortable feel and perfect balance - is one with a 4 5/8" barrel, and I also find no real difference in accuracy between the various barrel lengths.
My favorite is a 4 5/8" Vaquero - But I'll take and be happy with any Ruger SA I can get my
hand on.
Link: Ruger Single-Six - 7 round, 327 Fed. Mag included
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http://ruger.com/products/newModelSingleSixDE/models.html <