I have wondered too about the factory loadings. If that load book is the same as mine, it will show that 46gr of IMR 4350 will get a 180gr bullet to 2460fps in a 30” barrel (Nosler, Pg 10). I have read that Winchester and Remington factory loads clock-in for 30” in the 2440 to 2480 range so that Nosler load looks to be trying to match the factory loads. One thing for sure: They beat up the brass pretty bad and I have never duplicated such with my own loadings. You sure won’t see me shoving 46 grains of 4350 into my brass!