I've had really good luck with Vortex HST/PST scopes.

Currently I have a Strike Eagle 1-6x24 scope that seems to deliver poor performance.  The scope looks fine, I cannot identify any kind of mechanical failure or obvious defect.  I realize this is a less expensive product but it's still "not quite" right.

I've used the scope on three different rifles, trying to verify that the problem is the scope, and it consistently will not shoot a group comparable to other optics with same/rifle/same mount/same ammo and all things equal.  I have meticulously checked mounts and rings, all good.

Its seems like something mechanically in the scope is slightly loose or misaligned and the scope just doesn't perform as it should (but it almost does).  For example, shooting a mid-length AR with a Burris 1-4x24 and 77 grain SMKs from a supported position, I can consistently shoot around 1 MOA.  Switch to the (quite similar) Strike Eagle and the same ammo, same gun, same mount, same shooting position and it shoots 3-4 MOA.  I understand the "thick" reticle on this optic is not intended for shooting tiny groups but it shouldn't make that much difference.

Any thoughts?

Had this same issue with a buddies scope.  He had "tightened" everything up he said but the rings had inconsistent gaps and were not contacting the tube correctly.  Took it home with me and tightened the screws down consistently and torques the screws to the spec specified.  Remounted the scope on his rifle and problem solved.

First thing I would try is loosen up all the screws and retighten them alternating as you draw up the rings on the tube keeping the gaps as consistent as possible between the four gaps.  Make sure you use a torque wrench or drive that can tighten the screws to the correct torque spec for your rings or mount.  This is probably the most common issue I see with scope mounts is they are not torqued properly or cheap rings that have gaps when tightened to torque.  If you have gaps between the rings you are probably not contacting the scope tube correctly or the rings are just crap.  Not all rings are created equally and their are lots of crap ones out there.

Its been in multiple mounts on multiple rifles all evenly and carefully torqued.

Vortex will take care of you.  Call the CS line they will have you send it back and have you all fixed up.

Yes - give us a call or email. 800-426-0048 ext 6, or email [email protected]

Dawdled for a few days and then sent it in.  The CS rep I talked to on the phone was very helpful and I got the product back quickly.

The documentation included said the parallax was out of spec and the objective cell shifts with impact.  Repaired these issues and did some other general services too.  Sent it battery-less and got it back with one.

Pleased with the service and looking forward to seeing how it does.

Shot it this morning.  Works great, rifle shoots as expected again.