Hi,
I've done a good bit of load development for the 6.8 SPC's I use for hunting and the 7mm/08 AR10 I also use. I use exclusively magnum primers, normally the CCI 450, CCI 41 or the Wolf 223 for the 6.8, and CCI 34's for the 7mm/08. I'm really not terribly worried about slam fires, never...