I can tighten up the fitting of the upper/lower AR-15 receivers by installing a set screw that engages against the upper receivers retaining pin boss. The set screw can be accessed by removing the pistol grip. To adjust put a drop of Locktite on the threads, turn the set screw until the upper receiver movement is minimized. Check to see if the lower receiver pin can still be able to move with finger pressure. If necessary back the set screw off slightly until the pin can freely travel. This procedure can eliminate up to 95% of upper/lower movement.
This modification is not visible when the rifle is buttoned up. Price is $25 with trigger work or $35 with out.
Priority Mail return shipping is included in the price!
Any questions, please EMAIL me.