The misfire is because BR2 has a thicker cup. It needs seated with a slight crush and a strong firing pin spring. I shoot regular primers in a WSM with heavy loads of 4350. MattOnce the weather got cooler last fall during load development I got a couple hang/miss fires with the br2 so I switched to the 250 and had no more trouble.
Not sure what powder you're shooting and how much but I think the 6.5-284 needs the hotter primer for the larger powder charge.
I've always run Br2s.