Different brands of primers can make a big difference.I usually load with Winchester primers.I was only seeing about 15fps difference between WLR and WLRM primers.The Federal GM215M Gold Medal Large Rifle Primers was about the same velocity as WLR.I have some Sellier & Bellot Magnum Primers and my velocity dropped down about 50fps.I quit buying the regular primers and just buy WLRM primers now for all my loads in 308 Win and up.The 4350 powders are fairly easy to ignite.Some of the double based powders like Reloader 22 seemed to be a little harder to ignite.I had some hang fires and failure to ignite once with Reloader 22 and CCI 200 Large Rifle Primers in a 300 Win Mag.Could have been just some bad primers,but the only brand of primers I've had fail to fire was CCI.

~Molɔ̀ːn Labé Skýla~
As Bob Hagel would say"You should not use a rifle that will kill an animal when everything goes right; you should use one that will do the job when everything goes wrong."Good words of wisdom...............