Do you see unpredictable changes in Point of Impact? Do you think there is a problem with your scope? When was the last check you did on your BARREL? Scopes can fail and scope rings/bases can become loose. Sometimes, a loose barrel can cause POI shifts that are erratic. This issue was brought up in our Shooter’s Forum a few years ago. One member complained about his zero shifting from day-to-day — by up to two inches at 100 yard. Based on his erratic POI, he was convinced that he had a problem with his scope: “I believe my scope loses between 1 and 3 MOA each day.” When I shot my gun Monday, it was dead-on. On Tuesday, it was 1″ lower. On Wednesday, it was a further 1 or 2 inches lower. I don’t get it. The elevation knob was never touched. The scope will track and return perfectly to zero on that day. Everything is in order. What are the chances that the erector spring tube has broken? This is a Vortex GEO. “Never had a bad optic, but this makes me wonder”. LB On Forum member advised LB to return the scope to the manufacturer. Two other members suggested mounting it on a different rifle for testing. Good advice. It’s a good idea to try this before concluding that a scope is bad. Could the problem be the scope base?Two Forum members, ExPiper, and Dickn52 suggested checking the scope’s base, relating their experiences with problematic bases. This was a smart idea — anyone with a problem with POI should check all optics attachments. “Went nuts one day chasing impacts on a target at 100 yards. The shots would group well for three shots, but then go crazy for four. I cranked and re-cranked the machine for about an hour. The base of the rifle wobbled when I reached up. Removed scope, tightened the base screws and we were back in business.” –Dickn52 “Years earlier I had a shooting problem where shots would climb with almost every shot. I blamed the scope. When I removed the scope, I noticed the 20 MOA was cracked. It was getting wider with each shot. The problem was resolved as soon as I replaced the base. ExPiper Eureka Moment: The problem was not the scope, but the BARREL There were many helpful suggestions. But member PirateAmmo pointed LB to the true problem — a sloppy BARREL. “We had a trouble on a home built AR-platform rifle, barrel was a tad …”. Member Snert added: “Yep, I had a PC that suddenly went 19″‘ low. Picked gun up by the barrel and felt it wiggle. I tightened the gun barrel and the POI moved up 19 inches”. Problem solved — Barrel tightened up, POI back to normal
PirateAmmo advised the gentleman with the POI issue to check his barrel. BINGO! The barrel WAS loose. LB wrote: “Barrel was loose by 2%. I checked it twice and didn’t see it the first two time”. After LB retightened the barrel on his rifle, it started firing normally again. No more shooting 1-2 inches low. Problem solved. The fix was free and LB no longer has to send a perfectly working optic back to its manufacturer. What’s the lesson? Check ALL variables before you assume that a scope is bad. Check the barrel and the action screw tension. Also, the scope base and rings.
