Help with focal planes
I would like to put together a .308 bolt action for distances up to 1000 yards. I'm a little unsure of what kind of scope to go with. I've read over Zak Smith's optic guide but still feel uneducated.
From what I understand the first focal plane reticle shrinks and grows upon zooming and the reticle/BDC/mil-dots stay usable no matter the magnification.
So say we have a 4-16x second focal plane scope with a mil-dot reticle. Lets pretend it's zeroed at 100 yards on 4x and the mil-dots underneath stand for bullet drop at 200, 300, and 400 yards. If I now switch to 10x at 100 yards will the POA and mil-dots no longer be accurate? Would elevation need to be adjusted all shots apast 100 yards? I'm sorry if these are ridiculous questions, i'm just trying to understand.
Please explain this on a dum-dum level for me.
Thank you very much for your time.