Wednesday, 9 April 2014

.22" WMR Rimfire Magnum - Useful:


 The .22" WMR is a very useful wee round - if only it was cheaper to buy.

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!)

I picked this photo above to make the point that the AR15/M16 .223" really might be called a "mouse gun" when you observe that its bullet diameter is the same as the cheap as chips .22" Rim-fire - But its power is in a different class altogether. - Just look at the case sizes.

 -The .22WMR at 369ft.lb. with a 40gr pill gives more than three times the energy of the .22RF at 104 ft.lb. - But the NATO 5.56x45MM (.223") gives hugely more at 1,325 ft.lb.

The 22Mag  (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 22Mag 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 flatter shooting and harder hitting.


RUGER Model Ninety-Six in .22"WMR


Optimum barrel length for highest velocity in 22 Magnum, (.22"WMR) is around 18 to 19 inches'
- Optimum barrel length for velocity for .22" R/F Long Rifle is variously quoted as 14 to 16 inch.

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 path causing a loss of accuracy - this is another good argument for adding a silencer or 'sound moderator' - as these work by reducing the gases escape velocity and lowering its pressure.

 You really shouldn'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 22WMR bullet is .224 of an inch and the .22 Rim-fire is .223" diameter - so the bullet fit in the rifled bore must be somewhat compromised. - "Little John" rightly reckons that the compromised  rate of spin in the rifling would be more important than the slight bore  diameter difference.

     22 Long Rifle with 22WMR Ball, Hollow Point, and Polymer Tipped 'varmint' round.

The .22" WMR  is a very useful medium range 'Varmint'  and small game rifle cartridge available with various design projectiles weighing 30, 40, and 50grains. Excellent here for stretching the distance you can expect to hit rabbits effectively - but the ammunition while cheaper than centre-fire is still much dearer than .22 long rifle R/F - and can't be reloaded.

In America the 22WMR is held by some to be quiet 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 much LOUDER!)
                                     North American Arms (NAA) Five shot Revolver.

- & Look at the size of this barrel below!:

            Ruger Single Six Convertible Revolver with 9.5 inch barrel - That's pretty !

If you enjoy technical questions about ballistics and barrel lengths - The place to start has to be the Web-Site "Ballistics By The Inch" - BBTI - they have measured the velocities of the common calibres 'inch-by-inch' and put it all up on-line in table form. - Brilliant. - They've even had a look at the polygonal rifling versus 'land & groove' performance.

Marty K
After researching & writing 1,036 blogs I've got something NEW to try .. I've signed-up to Patreon. - In over five years I've not made one cent from this .. NOW you can send me a wee support $ - starting from $1. to get all this stuff from New Zealand - over a year that's nearly the price of one Shooting magazine. - Am I worth it?

https://www.patreon.com/user?u=16618870

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