So, if reloading is not a factor, what are the deal-breaking disadvantages of aluminum cased ammo as compared to brass or steel counterparts?
I wonder because there is a substantial weight diffence between brass and aluminum cased cartridges. It is very easy to percieve the difference by just picking up a magazine loaded with one or the other. If you had to carry a few hundred rounds the weight savings would be important. You would think that the military would have picked up on this but apparently there is something wrong with aluminum (or military procurement and innovation).
These are excellent observations and questions. I wish I had the answers, but we can go over some pros and cons. Now that the US military are apparently no longer going to sell their cases for reloading, there would indeed be a substantial advantage in the weight saved from the loadouts of our soldiers, if not other parts of the logistics chain. A standard loadout these days is what? Probably something like 150-210 rounds of 5.56x45mm in magazines plus another 100-200 round belt of 5.56x45mm or 7.62x51mm for the machine guns (correct me if I'm wrong). I think they'd definitely feel the difference, and even more so with actual loadouts of 600+ rounds that some soldiers sometimes carry (not sure how common this is myself, but it doesn't seem all that rare depending on the mission). Some other advantages are cost, once they're set up for volume production, and possibly the availability of materials.
One potential disadvantage of aluminum cases is feeding reliability with the type of aluminum cases I've seen, but if that can be fixed through some manufacturing process, then there should be no problem. Another disadvantage may be for us rather than the military, if lower volumes of brass are produced it may affect the prices we pay for ammo, but I can't be sure of that, as maybe the decreased demand for brass will lower the price of the raw materials in the commodities market. Honestly, unlike steel cases, which have their own advantages, it's kind of difficult to come up with any cons regarding military use of aluminum cases. Anybody?
Is it that aluminum cases don't handle centerfire rifle pressures very well?
It depends on the aluminum being used and the design of the cartridge. In the worst imaginable scenario, an aluminum case design may end up being heavier, costlier, and smaller in internal volume than its brass counterpart, but I don't see that happening based on everything else I've seen regarding aluminum cases. If there is somebody who knows better, then please set us straight on this.
Never heard of aluminum being used instead of brass. Only ones I know of are brass, nickle-plated brass and steel. Steel looks like a dulled grey metal, the nickle-plated looks like it's chrome. Of course I'm new to reloading and haven't shot anything but brass in a long time.
Aside from there being standard CCI Blazer ammo in the civilian market, the US Air Force uses aluminum cases in the ammo for the 30mm GAU-8 Avenger autocannon carried by the A-10 close air support aircraft. There are possibly other examples of which I'm unaware.