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I have a sigma, too. I like to sit and watch TV and dryfire the bajeebus outta it. pull slide, click; repeat.
I've come up with a way to rack and dryfire one-handed with minimal movement. you can get about a hunnerd fires in a quarter of basketball!
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aaaaaaaaaaaaaaaaaaand, I've used Blazer brass, as well as aluminum and never had an issue.