500grains, thanks for the advice ! I think 1:10 twist rate sounds good for my purposes, I will discuss it with the gunsmith. BTW, I didn't know that 400 grains Barnes X have a problem with stabilizing after impact. I used them on two buffaloes with success. They didn't perform as promised in those ads, which means the petals broke off more than expected, 86% weight retention on a X-bullet used on Cape buffalo and 76% with the newer TSX version used on savannah buffalo in Benin, so nowhere near the expected 99,98%. From the savannah buff the boys recovered another TSX that was bent at the tip and practically not opened up at all, but this propably happened when I had to shoot through some bush. It was a special hunt, the old warrior took ten .416 and two .378 bullets before he gave up, so many shots where follow ups. The cape buffalo died within seconds after receiving the X-bullet, Buzz Charlton said he had never seen a buffalo die that fast from a hit in the boiler room. Looked like premium performance to me !

Allenday, there are EAW mounts on the rifle already but with the open sights I'm not sure. I got a catalogue from Recknagel(ERA) and some of their open sights are looking usable. They make a universal front sight ramp that allows changing and adjusting of front sights, this combined with a fixed standing rear sight should work. What do You guys think about it ?

Kalunga