Although your load is not a hot load remember that magnum primers can boost pressure.  I don't know why you need them with 4350, it is not a hard powder to light and the Krag case is not a big case.  I use magnum primers in my Garand with WIN 748, as there was an occasional noticeable delay with standard primers, but it is a ball powder. I have never had the problem with IMR series powder in any rifle, even in extremely cold weather. The CC! #34 from what I have gleaned from the CMP forum is a magnum power primer, as military ammo is loaded with either ball or extruded powder and it works even in extreme cold with either powder.