I've never encountered anything quite like this and thought I'd see if anyone else has.

I have a custom .338-06 based on a Savage 110 action. Today at the range I shot 3 different bullets, 160 grain Barnes TTSXs, 210 Swift Siroccos, and 250 grain Hornady 250 grain roundnoses. All three grouped okay. I adjusted the scope so that the 250s hit the bullseye. But then the 210s hit 4 inches high (not unexpected) but about 8 inches to the left, and the 160s also grouped about 4 inches high but about 6 inches to the right! Any ideas?