The red dot is a variable. It was my own experience last year - but for the record I did buy this FF3 secondhand off fleabay, so possible I bought someone else's problem. It looked to be in good shape and was a good deal.
I missed one after sighting that used FF3 a week or two before opening day last spring. Shot it that same afternoon after the miss found I was 10 inches off. Sighted it back in, shot fine the following morning on another hunt, tag filled.
Ran a round through it to check POI couple months later before the fall turkey season, and it was 5-6 inches off again.
FF was awesome, they replaced it no questions, and the new one is on and sighted in. No issues now, its rock solid.