why aren't aluminum cases used for rimfire ammo?

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idek

New member
Aluminum cases are used for some ammo (Blazer pistol cartridges, for example). It's usually cheaper, because aluminum is cheaper than brass. The main drawback--as I understand it--is that it can't be reloaded like brass can.

But since rimfire ammo can't be reloaded anyway, why don't they use aluminum cases?

I imagine there's a good reason, but I've never heard it explained.
 
Z

zxcvbob

New member
I'd guess it has something to do with the properties of the metal. Mostly, the modulus of elasticity and the yield strength. The cases won't fail, but they might stick in the chambers enough to fail to eject.
 
4

44 AMP

Staff
The cases won't fail, but they might stick in the chambers enough to fail to eject.
Click to expand...


This seems logical. There seems to be a "length" factor involved as well. The common 9mm and .45 cases are short, and perhaps that is why the difference in the "grip" of the two metals doesn't matter there, but does when cases get longer. One attempt firing Blazer .357 through an early Coonan resulted in torn case rims.

The .22LR is pretty long, for its width, so aluminum might give issues.

then there is also the question of aluminum being folded into the hollow rim of the case, and being struck by the firing pin, without cracking....

and also there is the question of cost. Blazer might be cheaper in centerfire cartridges, but is it enough cheaper in rimfire (cost of production, which is more than just the materials) to justify using it? (assuming there is a suitable alloy?)

Never really thought about it, before, kind of interesting question, maybe call the tech guys who make Blazer ammo, and ask them??
Seems like they would have considered the idea, at some point....
 
Z

zukiphile

New member
But since rimfire ammo can't be reloaded anyway, why don't they use aluminum cases?

I imagine there's a good reason, but I've never heard it explained.
Click to expand...

Just a guess: it pertains to the rim and how that functions for primer ignition.

Steel isn't great; it's strong, but not soft enough to deform reliably enough to crush primer material in the rim.

Polymer could be soft enough to deform, but it would deform so much that it may not be strong enough in the case wall. Make it thick enough that the case wall is strong enough and now the rim is so thick that a .044 rimspace isn't going to suffice.

Aluminium has all those problems plus it doesn't form or machine as easily as brass.

Brass may be the goldilocks metal, soft enough to be easily machinable and deform when a pin hits, yet strong enough when even when thin.

That's my WAG, but the answer from someone who knows would be interesting.

Edit to add: If I were looking for an improvement in case materials for 22lr, I'd look to polymer before aluminium. Once you get the polymer formula right, you get IP protection for your formula, so there may be a pay-off in getting it right.
 
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M

Mobuck

Moderator
aluminum doesn't "flow" well in processes like those required to produce rimfire cases nor can it be made thin and soft enough to facilitate rimfire ignition.
 
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fourbore

New member
There maybe a cost/risk/benefit consideration. In 45 acp you have some real weight for brass in a box of 50. Looking at walmart pricing that seems to translate to about $2 a box of 50 from Federal? Give or take. How much potential saving for a box of 22lr? Say 10 or 25 cents a box of 50? Now what is the cost of new factory tooling and ammo development costs? As pointed out centerfire has a primer. Rimfire used the case as a primer.

This would be an interesting question for some "ask the company" web interface. Hornady or Federal might respond?
 
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FrankenMauser

New member
The original CCI .22 LR and .22 WMR shot shell loads used aluminum hulls, with the .22 WMR loads hanging on as aluminum until just a few years ago.
They dropped the aluminum, not because of the material properties making manufacturing more difficult, but because the rims cracked and ruptured at the point of the firing pin strike extremely frequently.
People didn't appreciate having a case (rim) failure rate of 50% or more.

Aluminum can't be annealed post-forming like brass, which left the rims in a brittle state. So CCI just went back to what worked.

I should still have some of both (.22 LR and .22 WMR with Al cases) floating around somewhere. If I remember and have the time, I'll take a look.

In the late '80s or early '90s, Blazer aluminum .22 LR hit the shelves. I saw bricks of it twice. Never again... :rolleyes:
 
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TruthTellers

New member
I've wondered about this myself, I think the reason Aluminum isn't used is that it just doesn't work as well as brass and the cost savings of using Al isn't enough to justify switching.

There's not much that can be saved in the raw materials of .22 rimfire, the true cost is in the labor of making the ammo. Changing all the raw materials to cheaper ones might save a penny per round, but make the ammo unreliable or inaccurate.

Not worth it.
 
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briandg

New member
My thoughts are that rimfire brass is much thinner than centerfire. Aluminum is just a terrible material for firearm jackets, it works for centerfire, but it's still clearly deficient compared to brass. Taking aluminum to a much thinner gauge and subject it to the sort of beating a semiautomatic firearm hands out would be nuts.

As has been said, using brass is obviously a big increase in the cost of materials, but I don't believe that an aluminum rimfire round could be made safe and effective. Too many flaws in that material.
 
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