Back yard caliber conversions .22 lr to .22 magnum?

[fat tony]

I heard of someone who had a Cooey #75 that was converted to .22 Magnum. Reportedly, it shot good for a while then the receiver developed a stress crack near the locking lug recess internal corner.

At first glance, it does not seem like such a good idea. However, if you were to sleeve the receiver to thereby double the locking lug recess contact area with the bolt locking lug(?).

I'm not sure if this would be such a good idea, and .22 magnum is expensive 'disposable' ammo. Just wanted to share this bit of information.

 

[camster]

Bolt handle on a Cooey 75 is the only locking lug, and it's just brazed on. The tale you heard is a better scenario than the handle shearing off, and the bolt coming straight out (into the face of the shooter). The concept of strengthening the receiver only increases the likelihood of the bolt handle failing. Not designed to shoot .22wmr at all, somethings gotta give.

These threads pop up every once in a while. Turns out there are some models of .22lr that could loan themselves to being converted (recent Savage 24 thread comes to mind) to .22wmr. Check out a rifle that has both .22lr, and .22wmr (or even heavier loads as in the case of the Savage 24's...). The cost, and efforts involved converting one makes just buying something already chambered in .22wmr a more viable option.

Anecdotal add-on...
The Remington 597 is a rifle that is chambered in both .22lr, and .22wmr. The actual differences between the models are pretty slight (doubled springs in the WMR, barrel, bolt, and a different magazine well/trigger group). You could easily own one rifle, and have it able to shoot either .22lr or .22wmr. The cost n' effort would still loan itself to buying 2 different rifles.

 

[lejarretnoir]

I get guys asking to convert their old Cooey to 22 Mag frequently.
The bore dimensions are not the same. 22 LR .217 bore and .222groove ,the 22 mag .219 bore and .224 groove . Also the rim dimensions differ. So now if you shoot a 22 mag in a 22 LR dimension barrel what would the pressure be?
I recommend a new gun as the cost to rebarrel and alter bolthead isn't worth it. Some smiths have successfully done it, but it depends on the action used to.

 

[fat tony]

Thanks for the info.

 

[singleshotom]

lejarretnoir is right on.
Ive seen several that so called G/Smiths re-chambered and its a poor practice.
Many Cooeys develop bad blow-back.
sst

 

[fat tony]

Many Cooeys develop bad blow-back.

Hmmmmm, that has got me thinking. . . . .. . .. . . . .. . . . . .

I wonder if it's better to use target velocity ammo with the Cooeys? I have heard people put anything and everything *.22lr* through them with no problems, but I am always open to new information.

Also:

I have a Cooey #75 *that I have no intentions on converting to .22 magnum*. This rifle came to me as a beater parts rifle.

I noticed some strange things about it over the time I had it.

I noticed these strange characteristics:

1: it looked like whoever had it was continually hammering the muzzle with a hammer and also there were some peen marks on the end of the receiver.

2: it had excessive headspace.

****

In any case, I cannibalized some parts off of that rifle to get another Cooey #75 going.

I came back to the original rifle lately to get it going.

For other reasons I had to remove the barrel and replace it.

Measurements of the inside diameter of front of the receiver and outside diameter of the barrel shank revealed that the interference fit once the barrel was installed was very minimal - it was almost a slip fit.

I did test fire it (not my greatest idea) and after 1 or 2 shots you could clearly see the barrel was advancing forward quite a bit on each shot.

Interestingly, I found that I had to replace the take down screw/ nut as it split as I was securing it one day.

singleshottom, everything you said points to the fact that for some reason the Cooey single shots do indeed develop bad blow back.

I am thinking that the blame for that might partially or entirely lie with the fact that the barrel shank does not provide enough of an interference fit, if you are unlucky and get an out of spec barrel shank.

I since got a replacement barrel and the interference fit was very much tighter.

I am going to have to try her out soon again to see if she will hold together.