Pursuing a childhood dream of an African Buffalo, I found a second hand Gebr. Merkel in Caliber 375 H&H Flanged Magnum. The rifle is a model 223 with side locks and scoped for driven hunts.
The plan was to use it on driven hunts on boar and red deer and get a working relationship with the rifle and to know how the bullet(s) perform before going to Africa. This has however proved to be somewhat a mission impossible for a number of reasons. I have used the rifle on driven hunts in the last season and also in the beginning of this season as well
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On driven hunts I prefer to use a relatively heavy slow, round nose (RN) type of bullet that will give a moderate exit wound roughly at the size of a golf ball, the bullet must exit to give a reasonable blood trail to follow, but still expand well and damage lung and heart tissue. The RN is preferred on driven hunts for security reasons as well as stability in a not always clan shot in dense undercover.

However all bullets that I have tried so far do not expand significantly, at least at the speed that I can reach with a reasonable pressure suitable for a double rifle. The Woodleigh 300 grains Weeldcore, 270 grains weeldcore and the Hornady Interlock RN in 300 grains have all been tested on boar and deer. The result is without exception that the bullet does not expand and the exit wound is roughly the size of the entry hole. This is also the case when hitting bone in the spine.
The chronographed speed is app 725 m/s for all loads, so it should be within the workable range for both the Woodleigh and the Hornady.

My second headache in this is that the double rifle does not perform well at this speed; 650 m/s give a reasonable clustering of the upper and lower barrel, whereas 725 m/s give a crossing of app 15 cm at 50 meters. These two factors work against each other, the bullet performance dictates a higher impact speed to obtain the required expansion and the barrel conformance of the barrels dictates a significantly lower speed. I have experimented with different powders VV150 VV160 and MRP2 , but no real difference here.

I could live with the lover speed of 650 m/s if only the bullet expansion this speed was acceptable but I haven’t found this bullet yet.

I could reregulate / re-solder the rifle to perform with 300 grains at a speed of app 725 m/s which I consider the maximum for the health of the rifle and me, but even at that speed the bullet expansion is not suitable.

In my other double rifle, a 7x65R Gebr. Merkel I use the most non-premium bullet I know of, the 9 grams Sellier & Bellot (a Round Nose) and the results have always been excellent on driven hunts as well as stalking for deer and boars. According to a friend of mine, these bullets are not worth the cardboard box they come in but my records show that S&B and I have shoot more than most hunters’ dream of in a lifetime.

The poor bullet expansion has lead me to think that the performance of these bullets on larger game will be similar poor, not that it will not kill a buffalo with a lung shoot, but it will simply take too long before it drops dead in its tracks. It seems to me that these bullets were created for bolt rifles in 375 with a slightly higher speed and pressure limit than what I can reach with my double rifle.

Any ideas or thoughts on the subject?