I see no reason to try and make a .270 out of a 30-30, that is nonsence..The 30-30 with a good 3X scope IS a 300 yard rifle if you can shoot..beyond that I wouldn't use it, as you will end up with too many broken legs on deer...
To me the beauty of a 30-30 is iron sights, easy to pack, good on a horse and a 200 yard deer rifle, that is what it was designed for and that is where it works best.
