What are you using to seat SA primers? I found that if I seat them with my Dillon 550, I regularly get misfires. If I seat them with my Hornady hand held primer seating tool, they are very reliable.I had a big problem with misfires when I first tried them. Turned out it was more the gun, though that gun didn't have problems with WSP prior to the SA primers. But the SA primers went off in every other gun I had, even the striker fired ones.
The strain screw was backed out a ways. So I guess they are a little harder than WSP. Loading with my Dillon I don't get any misfires anymore. My first ones I loaded on my single stage.