Robie

I don't think there is much difference between the two. Personally I would go for the 6.5mm but that is just a personal preference.

Tommies? They are vey lightly built and a .243 would kill them well enough too. Same for the duikers, impala, warthog etc. Big Five on this forum - he has been away for a while I understand - uses a .243 CZ on everything from warties and blesbok up to and including eland. I took my eland with a .30-06 but personally do like a little more weight as insurance, like an 8 mm up to .375.

Everyone always quotes Bell and his famous 7x57mm but he also used a .256 Mannlicker Schoenauer, which is in non-British parlance a 6.5x54 mm MS - the same amost as the 6.5x55. He liked to reserve his "big" 7mm for elephant so preferred his meat shooting of buffalo to be done with the 6.5. (note something people always fail to mention he actually used to recommend a 318 WR and a .450 as the ideal battery).

If you take a 6.5 mm (or a .270) do you plan to take a heavier calibre?

What are you planning?