Reloading for a new .338-06 with a 24” barrel (Shaw barrel on Marlin XL7) but IMR4320 loads are slow. All rounds fired over a chronograph with 180, 200, 225 grain bullets. Using load data from Nosler, Speer and Hodgdon the max loads are running up to 300 FPS slower than advertised. Starting load values lag approximately the same. However, loads with Varget and Benchmark perform very closely to the published values. I have been using CCI primers with all loads except for one batch with RP which appeared to be less accurate. The max 4320 loads showed no pressure signs at all (primer, brass, bolt lift, etc.). Have you ever experienced a similar result? I have been reloading for 30 years (rifle, shotgun, handgun) in over a dozen cartridges but this is my first foray into the 7mm + range. Thanks for your input.