These are the two calibers I finally decided on. The first mauser is almost done with the action alterations so that the 375 H&H fits in the mag box and feeds and extracts. This was a lot more intensive than I originally thought. At first I was using 300 H&H snap caps to gauge length since I had no 375. I got the 300 H&H cycling and decided to make sure the 375 would work as well since the C.O.L is supposedly the same. Well it was not. I had to extend the action another .050 for the 375 H&H to work properly. The 300 grain bullets are a little large for the width of the feed ramps and how it sits in the magazine so I will probably end up using 270 grain bullets. I have another mauser on the way to build the 300 H&H on which should go a little quicker since I know what is involved now.