I've been shooting Alpha SRP brass with GMM205M primers, H4350 with no ignition problems. Recently switched to GM205MAR primers and still no problems (after over 67 years of reloading these are the first primers I have used with a headstamp!). However, the coldest I have been shooting is in around the freezing mark.
It may be interesting what if anything you find out when you pull a few of the bullets in those misfires.
It may be interesting what if anything you find out when you pull a few of the bullets in those misfires.