It's easy to test.

Send the rifle to the range with a different shooter.

If groups remain large, it's not the shooter.

Clean repeat test.

If groups shrink, it just needed cleaning.

This is one of those questions that can only be answered on the range.

You didn't use logic or reason to get into this opinion, I cannot use logic or reason to get you out of it.

You cannot over estimate the unimportance of nearly everything. John Maxwell