I've only seen accuracy issues on paper when dealing with h414, for whatever reason it hated br2 and hated gmm primers but when using magnum primers it shot fantastic. The SD sucked but group size was great at 100 and 200 yards. With extruded powder I've never seen a difference though
I'd probably grab gold medal match magnum primers or the standard ones and just go with it. I've not done much testing with cartridges over 44gr of powder but I've seen the lowest ES/SD from GMM primers, followed not so close by br2 and normal CCI.