As compared to a copper jacket? No. As compared to cast? Maybe, depends on the alloy. Some alloys will withstand much higher pressure and velocity than thin copper with a pure (or nearly so) core which is what you would likely be working with. If you are using an Al jacket the same thickness as copper jacket (for a given caliber) I think you will find they will withstand higher pressure/velocity than cast but lower than copper.Question is.. Does the aluminium withstand higher speeds and pressures like in rifle calibers?
Al is a very (VERY) reactive metal and oxidizes nearly instantaneously with air. There are ways around this but none that would be economical if we are speaking about using them as jackets. If you are going to invest into the dies to make jackets, you may as well make them out of copper, there is nothing to be gained in the use of Al (other than some mass supply disruption). As an example of its reactivity if Al is mixed with Ga (Gallium, you know the metal that will melt in your hand) once dropped into water will split the water into O and H and produce Aluminum Hydroxide leaving the Ga alone to be reused. Nifty science experiment for the kiddos and much fun for a 'hold my beer and watch' ensemble. Actually just mixing the Ga on the Al is rather fun to watch, grab a soda can, warm up the Ga in your hand, scratch the surface of the can and put the Ga on the scratch, it will eat through it rather quickly, making the aforementioned blend you can then water drop.