Re: ACI cosine indicator. Warrenty??
If the screw keeps coming loose, perhaps the thread locker has been removed? If that is the case, I would suggest utilizing a Very Small, Minuscule amount of Blue Lock-tight on the Interior threads of the screw hole at the time of reassembly. This is at your own risk as you do not want to get any of it on the washer or hub as it will cause a loss of smoothness. Or if you prefer, I am more than happy to apply new thread locker onto it for you. If you prefer that I do that, please scribe the seam (witness mark) of the ACI body and base to where it is leveled / zeroed to the bore of your barrel, so I can reassemble it to your same zero.
In addition, IF you have not invested in an inch pound torque wrench such as "Snap On's," which is calibrated for lighter readings, and which you can also utilize when tightening the screws on your ring caps, I would. It isn't too time consuming to check the tightness / torque settings of all screws and nuts before shooting. This is a mandatory procedure that All Military, Federal and LE Shooter's are taught when they go through school. Before shooting, or going out on a detail, or "Outside the wire," they always check their scope ring nuts and receiver screws, setting them to the manufacturer's specified torque settings.
If the receiver screws are not constant, the weapon will not shoot the same POA / POI.
If the ring nuts are not constant, the weapon will not shoot the same POA / POI.
If the bases are loose, the weapon will not shoot the same POA / POI.
If the ring caps are loose, the weapon will not shoot the same POA / POI.
If the ACI Screw is loose, the weapon will not shoot the same POA / POI.
I hope that I have been helpful in this matter as that is my sincere intent.
My Very Best Regards,
Ward W. Brien
Sniper Tools Design Company, LLC