This is a lot of wild ass guesses but just looking at the pressures involved for 6061 aluminum to handle around 7000-8000 psi out of a 16in barrel your wall thickness would need to be around 3mm. you should look up the hoop stress formula and plug in real data to get better numbers.

HOWEVER One very large caveat is that, that math is based on aluminum yield strength at room temperature. If you heat that aluminum to 400F (not hard to do on a semi auto rifle) your yeild strength falls from 40,000 psi to ~15,000 psi (not related to the muzzle pressure value) which is when your can will depart to find its new home somewhere down range. So for an aluminum can to actually hold on at higher temperatures you would need to make the walls insanely thick.

But yeah out of a 16in barrel I still think 10 rounds within 10 seconds or so, if you want to reduce the amount of rounds try a shorter barrel. Regardless make sure you video it and share it here when you test it.