The cap attaches to your mag ring???
I have his caps on a Leupold MK 5 and it tightens up to the ocular and does NOT attach to the mag ring. Now, I did have to move a mag throw lever about a bit on a Viper on my .308 to avoid bolt handle interference, but not with the Leupold AAD caps.
They do hold on tight....bit of a pain to get them closed sometimes. he suggested a light film of oil until they wear in a bit....didn't find that to work that well but with a bit of experience, I can get them fully closed without struggle. But they will not open by accident and that's what I wanted.
And they are very well built.
I also see that MK Engineering is now offering printed caps very similar to AAD....but I don't know anybody who has fielded them yet.
Cheers