Wow, this sure didn't answer what I thought was an interesting question.
I don't know the answer to the question, but am interested in hearing from those who do.
I advise you to forget this caliber and buy .270 instead. Ammo is difficult to find and when found selection is non-existent. The .264 came out in late 50s therefore fewer guns were made in this chambering making them more expensive to buy. When compared to .270 or 7mmRemMag the .264 has absolutely nothing going for it. Buying rifle in .264 is like buying pistol chambered for 9x18 Ultra (the 9mm Browning or 9x17 is far, far better choice).