Good to see the pic. I really dont like having other people shooting on my targets. It's like stirring someone else's porridge.
I do remember now I've had this myself once where the scope base screw had come loose ( two piece base and ring system). Had more of a random wandering up and down over 15cm than actual double grouping. The other time was a mate's P14 just got it sighted in at "25" and the check shots were a foot away. Sighted those in and after a while found we couldn't hit a rolled out close cell foam. The wood in the stock had split. Sorted by buying a new rifle and never looked back ...
Anyway I dont think you've said, "bases screws- check !" Yet. If youve got it apart for the hot glue job you might as well dismantle the whole mount system and reassemble it with loctite while you're about it.
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