I would just load up the 200 or so rnds that U plan on and let him shoot the gun and get used to it....as most reloaders know not all loads work the same in every rifle....me I would kill for some real 150grn winchester silvertip bullets!!! they are very deadly in my .300, I use them for elk all the time or I should say when I can find them and load some up....but then after he gets back home U can work up a load for him, that U both have confidence in!!!!