yes, I had a neighbor do it when I was a kid. He annealed the necks though to make the stretch easier, he said the cases lasted longer when he did that. 270 brass is cheap and easy to get. I take it you just have a bunch of 30-06 brass laying around? The longer neck of the 270 was prone to splitting after a couple of loadings if didn't anneal the necks first or so he told me. I have never done it my self, because I have a 30-06 and a 270 and wouldn't want to make amistake with wrong headstamped brass.