My thinking is that if you're trying to build a lighter rifle, it needs to use a light bullet (but still heavy enough for deer) and as little powder as possible to keep the recoil low enough to be comfortable. A 6BR with 85-95gr bullets is great for this, but you may have to tinker a bit if feeding from a magazine is important. I use a single-shot 6BR (Stiller PredatorV action) for my deer/pronghorn rifle, so feeding from a magazine doesn't matter to me.
The .243 will use ~15gr more powder than a 6BR, but it will feed reliably without any modification to the magazine, extractor, or ejector.
As you go up in caliber from 6mm, the bullet weights go up to retain the same BC as a 6mm -- that means more recoil.
I don't like muzzle brakes on hunting rifles, but they certainly do reduce recoil.
The .243 will use ~15gr more powder than a 6BR, but it will feed reliably without any modification to the magazine, extractor, or ejector.
As you go up in caliber from 6mm, the bullet weights go up to retain the same BC as a 6mm -- that means more recoil.
I don't like muzzle brakes on hunting rifles, but they certainly do reduce recoil.