Yep try handloading. A but more velocity might bring the groups together.

I assume you are shooting a Right/Left, a Right/Left, not shooting each barrel individually.

And also shooting each two barrel group with reasonable speed, ie only a few seconds in between shots eg say seven. Though I would guess in theory, if the barrels are warmer, ie a shorter time period I would think the expansion would push the barrels apart more.

I would have a lot of trouble accepting a four MOA "group" in a small double calibre such as 7mm. Irrespective of whether each barrel is shooting well.