Readjustment of Fixed Parallax Scope

I was given a scope that has no parallax adjustment. It is fixed at 50 yards. I was able to unscrew the end part where a AO would be. My apologies for not having the correct terminology.

Anyway I unscrewed it from the scope and within it was the lens as well. Is that normal,like how it is supposed to be?

So I set up a Target at 25 yards which is what I want my zero to be. I then screwed it back into the scope until I could not turn no more, basically I bottomed it out. After unscrewing it two whole revolutions I was then Parallax free or had the very least amount of parallax by doing the head Bob method.

My question and concern is there any shortcomings of doing this to the scope? I mean lets say that you have finally zeroed your rifle and then start to plink or shoot at whatever. Being that you just unscrewed and screwed the glass back in will that recoil or amount of time shooting affect zero? because it's not totally tight on a scope?

I hope everything makes sense and I hope to hear from somebody soon as to what should and should not do and any advice or suggestions will be greatly appreciated.

Thank you and look forward to seeing your replies.
 
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I never can get a good blade to fit the lens nut thing then if i do the notches strip before it turns. Maybe im a doing wrong? ( Cheap scopes to practice on >45$ stuff).
Some are reverse thread🎩🤙I've never had to use a "tool", just grab and twist. A little strip of rubber for grip helps though
 
I had one cheap scope came in a kit with a QB78, I throw it in a drawer some ten years ago. Last week I tried my other target scopes no one could focus below 10 meters, and I remembered this old one ... it toke me a half a day to dig it out from my lockers and looks really like a new after all these years ;)
This scope was even worse, maybe about 20 M focus. But I managed to brake loose the front ring, and voila...
readjusted the short focus to some 4-5 meters and now it maxing out about 20 ish.
I got a perfect squirrel poking scope for peanuts.