Indeed , the diffrence will be the shooting situation .
- driven shooting
- a well placed bullet from a high seat at reasonable light at about 50 meters
- a crop protection shot , after a farmer has been seriously complaing for about 2 weeks and you HAVE to do something about .
I wouldn't like to feed the moose that are killed every year in Scandinavia with the 6.5X55 . Would an average sized boar be harder to kill ? I don't think so . A 140 grain Nosler Partition out of a 6.5 will certainly kill the average ( 30/60 kg ) boar with a well placed shot . In France there is a ban for military calibers , the same law existed in Belgium , but this changed recently . Tousands of boar in these countries will be shot driven with browning Bar rifles in 270 and remington 7400 in 280 . Are these perfect ? I don't think so . The 270 with a good bullet will certainly kill larger boar with a well placed shot .
In a 270 I would use 150/160 grain bullets like Nosler Partition , Sako Hammerhead , Norma PPC Vulkan , etc .... Certainly when the boar would be driven .
When the shot frequently is less well placed . Like shooting driven boar or at a boar which is in mais or other crops every bit of advantage you can get is welcome . A bit of extra frontal ( bullet) area and bullet weight never do any harm . For driven shooting a 8mm or 9.3 mm will be excellent . The same can be used for " still " hunting .
A 30-06 will make another great round . A good 180/200/220 grain bullet will penetrate the heaviest boar and kill them .
The same for a 308 . What normal sized animal will survive a well placed 180 grain bullet from a 308 ?
In any calibre , stay away from those soft bullets when the game would be larger . Use Partitions , Hammerhead , Super Hammerhead , Barnes X , Vulkan , Oryx , RWS EVO , TIG , TUG , DK , etc ....
In Europe the Brenneke TIG and TUG have always been very popular . This has a reason .