Cooey 84/840 receiver max pressures?

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aesache

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Does anyone know what a Cooey 84 receiver is good for max pressure wise? I have a bunch of old 12g Cooey's that I was thinking of re-barreling via the "stub gun" method.

Think i could put a 357 Mag safely on one of these. I know this has been done with the H&R receivers (both SB1 and SB2) but cant find any info on the Cooey 84's

I am only really interested in doing this if i can use the 84's reciever as I have enough parts to make a few of these in pistol calibers.

I have enough cut offs and misc parts lying around I would like to make one of the following

762 TOK
45 ACP
357 Mag
9MM
 
So does that mean that the Cooey 84 is stronger than the H&R SB1 frame and equivalent to the SB2.

303 and 30-06 are WAY higher pressures than anything I would be doing. 30-30 would be cool though i hadn't considered it as I assumed the pressure would be too much

Again pics would be really cool if you have any

Blessings
 
Lots of things you "can" do that may not be wise.

There are pictures on the Alberta Outdoorsmen forum of a Cooey 84 which failed at the thickest part of the breech with a Steel shot BB load.

Your fingers and eyes, your choice.
 
Its not just pressure only as in hoop stress, its pressure X cross sectional area as in recoil force ... If you do some elementary math, you should be able to answer your own question. (BTW - shotshell pressure is ~ 12K psi.)
 
The design itself is identical to modern low end (Baikal, H&R) single shots in high powered cartridges. However my concern as this has been on my to do list as well would be a sudden crack and sudden failure, particularly with the locking bar. The 840 seems like a low carbon casting.

I figured a 20 gauge and 7.62x25 would be fun. But I would not try a full on rifle cartridge simply because the receiver is just not made for it and in particular, neither is the locking system. I think the lock would fail first. Fwiw.
 
Some things to consider...
The receivers are cast, and are not investment cast steel. I suspect malleable iron, but don't know.
The firing pins are large diameter - OK with shotshell primers, probably OK with any cartridge that produces similar pressure. Otherwise, bush the firing pin.
Later ones had locks made of sintered material. Earlier ones were steel.
How is the underlug fastened to the barrel? Failures have occurred.

When doing calculations, consider backthrust, which is dependent on the area of the casehead. A smaller, hotter round may produce less backthrust that a larger lower pressure one.
 
Listen to the caution tiriaq is giving you.

Back in the day I has similar aspersions in creating similar rifles on these actions. They've always been cheap and plentiful and installing sleeves has been going on for a long time.

Now as mentioned, not all of these actions were created equal. They were originally produced to shoot different gauge shotshells with standard pressures. Even those relatively low pressures were hard on some of these shotguns. I've seen a few that were converted to 44 mag, with the firing pins bushed and they very quickly developed rings on the receiver faces from the backward pressure of the cartridge being fired.

If you are insistent about doing this, consider the cost, if you can't do the job yourself. Likely you can pick up one of the later knock offs of that action, which is made from strong steel much cheaper. They come up regularly on the equipment exchange.

Most of the old Topper actions were made of cast steel. Maybe all of them. They're the same action with a different name.


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bearhunter said:
Listen to the caution tiriaq is giving you.

Back in the day I has similar aspersions in creating similar rifles on these actions. They've always been cheap and plentiful and installing sleeves has been going on for a long time.

Now as mentioned, not all of these actions were created equal. They were originally produced to shoot different gauge shotshells with standard pressures. Even those relatively low pressures were hard on some of these shotguns. I've seen a few that were converted to 44 mag, with the firing pins bushed and they very quickly developed rings on the receiver faces from the backward pressure of the cartridge being fired.

If you are insistent about doing this, consider the cost, if you can't do the job yourself. Likely you can pick up one of the later knock offs of that action, which is made from strong steel much cheaper. They come up regularly on the equipment exchange.

Most of the old Topper actions were made of cast steel. Maybe all of them. They're the same action with a different name.


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Click to expand...

Guess I always look at these skeptically. Some of those are obviously cast and it's a big step up from shotgun to rifle pressures.

Grizz
 
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