I have seen a few rifles that would hold onto nickeled brass but were fine with regular brass. One was a Stainless barreled 7MM Mag with a chamber polished to a high sheen, and yet it still would "grab" nickeled brass. I am at a loss to enplane it in all honesty.
I thought I'd just mention it and then ask if your "sticky loads" are made with nickel plated brass?
