With an idea from my pal Jesse Shaver (BluZi on RFC), I have started building semi auto 22 magnums.
My plan is for it to use Ruger 10/22 magazines and 10/22 or 77/22 barrels.
In theory, the same platform will accept 22LR, 22WMR, 17HMR, and 17HM2.
Blow back actions rely on the mass resisting the cartridge for successful operation. Designs that use heavy or multiple springs have missed the point.
My resistance mass is close to 1-1/3 pounds. This is more than enough for 22WMR. The mass can be easily reduced for less powerful cartridges.
The first prototype works with 22WMR, but has some extraction problems. Probably due to my home made extractor.
I wanted to use the Ruger type, but didn't have enough room for it.
The second prototype is in progress and incorporates several changes that I am hoping will make it reliable. Now I have the Ruger extractor in the bolt.
5 Feb 2011
The second prototype has been tested with three brands of ammo.
The new extractor works well, but I still have an occasional fail to cock so I reduced the recoil spring.
Now I have the occasional fail to chamber.
7 Feb 2011
I have reduced the bolt mass and returned to the original recoil spring and just fired two full (9 round) magazines with no function problems at all.
Out of ammo again! I have ordered a Shooter's Ridge magazine to see if it will work with an after market magazine (and more ammo!).
9 Feb 2011
I am looking to re-design the bolt to make it simpler. If I can get a workable design out of the computer I will start building it.
Anodizing starts today.
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