Just put a new to me Vortex Viper PST 6-24 FFP on my Savage .223 to replace a BSA 4-14 FFP, both 30mm tubes. Both claim very similar max adjustment of ~20 mil. I removed the BSA (which had plenty of adjustment to get to 750yds but needed a small hold over 2mil to get to 1000) and screwed down the Vortex. A quick bore site and 2 rounds later, I am zeroed. Did not touch the ring to gun connection at all, just opened the tops. BUT... Looking at the scope, I am set to 20 mil. I adjusted out to 21.1 for a 300 yard shoot, but I have no adjustment left. I do not have an angled base, but really should not need it until a 1000 yd shot. Right? Is there a chance that there is some combination of zero stop + incorrectly installed cap that could be causing this? Why am I am t0 mil before I start? Is it required to have a 40MOA (sorry for the unit change) base, in order to use this scope? I have not taken the scope apart to see what is going on, but that is my next step. Just wondered if anyone has experience with this and what may be going on. I am hoping the prior user took off the cap, jammed too may zero stops in (or in the wrong place) and screwed the cap on in an "elevated" position. Plausable?? Thanks.