Some of us may wonder at times how much of an improvement in velocity can be had when the more expensive .22 magnum (WMR) round is used in a short-barreled handgun. At one time I chronographed for a friend his .22 LR/WMR Heritage Rough-Rider revolver with both rounds. The results seemed to indicate no improvement, but he kept the data and I have long forgotten the results.
So I have once again re-shot both rounds out of a revolver over the chronograph and have the results. Ammo was 2 varieties of .22 LR High Velocity, 1 type of Hyper Velocity LR, and 1 type of .22 WMR ammo. Temperature was 70 degrees. Chronograph was the Oehler 35P @ 10' from the muzzle.
GUN: Ruger Single-Six revolver 4 5/8" barrel
LR Load #1
Winchester Super-X 37-gr HP
Average 1070 fps
SD (standard deviation for all shots) 19
LR Load #2
Remington Golden Bullet 36-gr HP
Average 1049 fps.
LR Load #3 (hyper-velocity)
Aguila Super Maximum 30-gr HP
Average 1327 fps
Mag Load #1
Winchester Super-X 40-gr JHP
Average 1369 fps
The same .22 mag load as above from a 20" barrel Winchester Model 9422M rifle
Average 1864 fps
CONCLUSIONS: Unlike my previous tests using the Heritage revolver, not only were velocities higher overall for all rounds tested in the Ruger, but the .22 WMR showed an actual gain in velocity, even from the short 4 5/8" barrel of around 310 fps. But the cheaper .22 LR Aguila Super Maximum ammo was only 42 fps. slower than the .22 WMR, albeit with a bullet 10-grains lighter. I am sure the use of 30-gr WMR ammo would widen the gap, yet it is good to know that you can get that close with .22 LR hyper-velocity ammo. Be aware the Super Maximum is the fastest hyper-velocity ammo out there. None of the loads were tested against each other for accuracy but the high standard deviation of the WMR ammo (66) would make one wonder if accuracy would be impacted. Accuracy in .22 guns can vary quite a bit from gun to gun anyway, so you need to do your own testing.
So yes - the .22 Mag is faster, even from barrels only 4.5 inches long. However it loses around 500 fps. over rifle velocities while the LR ammo is only around 200 fps slower in this case from the factory listed velocity of 1280 fps.