It was introduced by Winchester in 1959 - but they didn't sell a gun in that chambering until 1960. - S&W, Ruger, and Savage all beat Winchester to the market there.
22"LR, .22"WMR, 5.7x28mm, 5.56x45MM (.223")
(We're all '22's together!)
That photo above shows that while the .223" really might sometimes be called a "mouse gun" having the same bore as the cheap as chips .22" Rim-fire .. its power is in a different class altogether. - Just look at the case sizes.
-The .22 WMR at 369ft.lb. with a 40gr pill is also in a much higher class than the "two-two" - giving more than three times the energy of the 104 ft.lb. Long Rifle. ( The NATO 5.56 x 45 mm (.223") gives hugely more at 1,325 ft.lb.)
The 22" Mag (WMR) is obviously a bigger rim-fire case than the .22" long rifle RF - being longer and slightly fatter - but it is also made using thicker stronger brass to safely operate at higher pressures. The 22 Mag can send its bullets off at over 2,000 feet per second from a full length rifle barrel and around 1,500 fps from a typical handgun. - So it's "flatter shooting" and harder hitting.
Optimum barrel length for highest velocity in 22 Magnum, .22"WMR is around 18 to 19 inches
- Optimum barrel length for .22" R/F Long Rifle is variously quoted as 14 to 16 inches.
- So what's your guess about the muzzle velocity from a 1.25" revolver barrel having a cylinder gap?
Standard Manufacturing S333 THUNDERSTRUCK .22" MAGNUM Revolver.
- EIGHT CHAMBERS - FOUR Shots - 1.25" Barrel:
I really do like this concept of the twin barrel - two-hammer self-defence carry gun using a two finger trigger press. This design could enable folk living with hand injuries / amputations or arthritis to be able to shoot effectively. - BUT consider this .. That trigger pull is around 23 pounds and really needs the two fingers to achieve it's l.o.n.g mushy stretch.
And - reflect on just WHY the wee Thunderstruck two barrel handgun is so called .. surely the roar of two WMR cartridges discharging together from the stubby 11/4 inch barrels will assault your unprotected ears with an almost physical blow .. I'd guess that the WMR caliber choice was for marketing reasons .. "TWO MAGNUM ROUNDS FOR EACH PULL OF THE TRIGGER"
And to what purpose? .. Those "Magnum" bullets will be lucky to make anything like 800 ft/sec before they exit those stunted tubes .. no faster than the quieter Long Rifle rounds would manage.
Note: We are considering only velocity here - Shorter barrels will in general give a louder report as the gasses will exit at higher pressure.. High velocity gasses may overtake the bullet leaving the muzzle and slightly unbalance the projectile's path causing a loss of accuracy - this is another good argument for adding a silencer or 'sound moderator' to your guns - as these work by reducing the gases escape velocity and pressure.
NAA 5 Shot Dual-Caliber Revolver.
4 Inch Barrel Should Work OK:
You really mustn't think that you can safely use RF in WMR chambers despite the smaller 'Long Rifle' .22" going into the WMR chambers (It does not fit). If such double use is wanted you can buy some brands of convertible revolver with swappable cylinders.
This interchange seems to work OK despite the difference in bullet diameter: The 22 WMR bullet is .224 of an inch and the .22 Rim-fire is .223" diameter - so the bullet fit in the rifled bore might be somewhat compromised. - "J" rightly reckons that the mismatched rate of spin in the rifling would be worse than the slight bore diameter difference.
22 Long Rifle with 22WMR Ball, Hollow Point, and Polymer Tipped 'varmint' round.
In America the 22" WMR is held by some to be quite a useful self defence calibre for very compact (sub-compact) handguns and 'Derringers' .. rather than the .22" Long Rifle R/F - but there really isn't much difference in velocity between the two rounds out of a two or three inch barrel (but the 22WMR will be impressively much LOUDER!)
We live in an era where PERCEPTION has become reality .. "It sounds much louder/more powerful".
RUGER Single Six Convertible Revolver Has A 9 1/2 Inch Barrel ..
And Is Beautifully Made - Quality Can STILL Be Found:
The Keltec PMR 30 s/a 22 Magnum pistol claims to have been around USA since 2010 - and uses a 4.3 inch - 109 mm barrel to release it's load of thirty rounds from quad-stacked magazines. My guess is that it will still be LOUD .. but a fellow club member is tussling with our irrational licensing regime - who currently are denying him entry and Customs release of the first ever specimen to land here on permit.
- This post is an 'updated' version of my earlier .22 Magnum post:
.. I've signed-up to Patreon. - after five years writing now you can send me a wee support - starting from $1 - for all this stuff from exotic New Zealand .. yes most everything here is indeed EXOTIC .. apart from those interesting native birds eh.