There are no aluminum head shotshells. The silver coloured ones are steel. The problem with steel is that it doesn't shrink back after firing, like the brass head shotshells do.
Having said that, guns that have a highly polished chamber, are much less likely to experience the problem of sticking shells.
Winchester AA, Remington STS and Remington Nitro27 still have brass heads on their shotshells.
I have a flock of guns that do not experience sticking shells - Benelli, Beretta, Browning, Bernardelli, AyA, Winchester, Cooey - you get my point.
Most of the world uses shotshells with steel heads - lots of them on premium brands like Fiocchi and B&P.
Having said that, guns that have a highly polished chamber, are much less likely to experience the problem of sticking shells.
Winchester AA, Remington STS and Remington Nitro27 still have brass heads on their shotshells.
I have a flock of guns that do not experience sticking shells - Benelli, Beretta, Browning, Bernardelli, AyA, Winchester, Cooey - you get my point.
Most of the world uses shotshells with steel heads - lots of them on premium brands like Fiocchi and B&P.