you can shoot all the aluminum cased ammo you want, but, it's just not recommended in a blowback operated firearm. What happens is that upon cycling there is still some powder burn in the casing, and without a fully supported chamber (due to the blowback operation) you risk over pressure of the casing which can split the casing...or worse. With steel cased ammo, we all have a tendancy to think it's just "dirtier" due to cheaper components, but there is more to it. Steel cases do not expand and "fire form" to the chamber the same as brass, thus, some of the powder residue escapes the into chamber, and into the action. Steel cased ammo is going to be a bit harder on your extractor as well, but possibly not enough to cause a problem.
Aluminum cased ammo is fine in a locked breach type firearm, but can be problematic with blowback operated guns.
That's just some info I've picked up over the last 5-6 years from my Kel-Tec buddies. Take it for whatever it may be worth.
surv
