Barnes has been in to the "mushrooming" copper alloy bullet for a while. I suspect as the market develops, others will enter. Probably develop all sorts of non-toxic alloy bullets that approach lead like densities. Much like have been developed for shooitng migratory ducks/geese.

I do not use Barnes bullets. It is still OK down here to use jacketed lead core bullets. I think I am right about this .... for a given grain weight, the Barnes' bullets are longer than typical copper jacketed lead bullets because they are less dense. They do not actually "mushroom" but rather they "expand" by folding back pre-formed "petals". You may already be aware but the 308 Win. case is fairly short. The longer the bullet, the less the "powder" space. If you have to go with a less dense bullet, I suspect that 165 gr. +/- is about as heavy as you might want to try.

I know two guys that use the Barnes bullet are avid hand loaders. One for a 270 Win. and the other for a 7mm STW. Both love this bullet and both have taken white tail, feral hog, mule deer, elk and black bear with their setups.