The last 270 I owned shot the Blue Box better than anything else I had on hand. In the 90s I asked a guy I knew in Federal's ballistic lab what powder was used in several of their loads and something similar to Win 760 was the answer for most of the loads in question. I have gotten similar accuracy in my attempts to copy the factory loads but velocity was a little low when I hit book max. The difference was not enough for me to care as accuracy was there. I'd guess one could look at Western Powder's offerings and come up with something closer if one wanted to stick with a spherical powder.
