You can always call and ask them.
I don't know Millett in recent years, but many scope makers do not test certain scopes for a given recoil force. That doesn't mean that they won't handle something.
As with many things, it's about numbers. When I bought my first Primary Arms scope, they didn't say no; but recommended against using it on a 308; so it's on my Creedmoor.
By the calculations, those two rifles recoil with a very similar force. I have over 1,000 rounds fired through that Creedmoor so far, and zero issues with the scope.
Cheers
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