Both the Browning BAR and the R1 are great guns.I do like the recoil reduction system on the r1 when it can so caled make a 300WSM feel like a .270.If I had to pick 1 caliber to get the R1 in I would go with the 30-06 becuase it can be used for any big game in North America.Now if you plan on getting it in a 300 Winchester Mag I would then also get a .270 Mag Barrel with it.The only thing is that you will have to change your sight and take the gun in to the gunsmith every time you want to change out your barrel thus is why I would buy it in 30-06 and be done with it.If you have any other guns thatare of alighter caliber then a 300wsm would be a good choose for your larger big game animals.