I have a single six that has cylinders for 22 LR and 22 Mag. Even though I had the revolver for over 20 years, I had never used the mag cylinder and one day I was just curious to see what it would do. Now this was my silhouette gun so it had the 9.5" barrel but I was surprised how fast the mags were so to say a 300-400 fps gain over a 22 LR is very believable. YMMV.