First, sorry its not an good old magnum M98, but...

Have been wanting a big bore for some time, so I broke down and ordered a Ruger RSM .458 Lott a while ago. Well, it seems Ruger has problems delivering, because the rifle didn’t arrive. (in retrospect, not that it was entirely unexpected as a friend also ordered one in 416 and he waited over a year and no gun.)
So I changed to a Mauser M03 Africa instead. And it arrived about a month later.
Went straight to our cabin got the reloading equipment ready. I bought some Rem. 300gr bullets for practice rounds and started with low powered loads as my experience with bigbores are limited to 3-4 rounds of the bench with a friends CZ 416 rigby some years ago. (plus a Wby 340 I owned though it isn’t a bigbore).
I found that the 300gr at approx 2650fps made for nice practice rounds for now. Next came a few Barnes 450gr TSX. With those I stopped at 2242fps. With Hornady 500gr FMJ, I stopped at 2026fps.
Recoil wasn’t as much as I expected. I wouldn’t like fire a lot of these rounds in one afternoon at this time, but a few rounds at short-moderate range shouldn’t be a problem. Will probably try some more powerful loads the next time I get the chance.
All in all, I shot 39 rounds that day.

My impressions of the M03 so far:
The rifle including mount and a leupold VX-III 1.5-5x weighs 4832grams or 10.65lbs. Rifle alone is 4396grams or 9.7 lbs. Stock length was just right for me and excellent balance. The pistolgrip have a slight swelling on the right side to better fit the palm of the hand. Easy take down allows one to carry it in an inconspicuous case if you choose.
It has a 4 round detachable magazine which you can secure to rifle with a supplied Allen wrench for situations you don’t want to risk it dropping out.
The sling mounts have integral loops and not the often used Uncle Mike’s. But they are perhaps more quiet as they don’t rattle as much. The downside is that not every sling can be used.
I also looks like Mauser has used the standard recoilpad they use for all rifles. It has a 4mm spacer and a 8-9mm pad. I might change that to a 1" Pachmayer Deccelerator , but the stock will probably have to be shortened. And I’m not sure how that will work with the Kick Stop in the stock.

All in all, I’m very happy with the rifle. And the caliber changing feature is VERY nice to have in countries like Norway where buying extra guns isn’t as easy.

One question here at the end.
Has anyone done any penetration tests with 300/350gr TSX (or 350 North Fork) at moderate speeds (2500-2600fps)?
I’m considering getting some for use on elk/small moose but are not sure I get the chance to test them any time soon...