Aluminium gas checks

[wildcard6]

Does anyone have experience with aluminium gas checks for cast lead bullets as opposed to copper? Alum is so much cheaper than copper, but I'm looking for anyone who has actually used them and their opinions on their performance. With everything going up in price, I'm looking for bargains/savings wherever I can find them.

[LawrenceA]

I use them on my 223 and 30-30.
No worries so far but I am not chasing sub MOA results