May 11, 2022: Scopes go bad — How to diagnose rifle optics issuesRiflescopes can be described as mechanical contraptions. One of the most frustrating aspects of precision shooting is the possibility that your scope will fail. If you’re lucky, it won’t happen during a National-level competition. It’s possible that the failure won’t be so dramatic and obvious that you don’t have to spend months trying find the cause. Scope problems can be difficult to diagnose or can be unpredictable. Unexplained flyers, or a slight decrease in accuracy may be signs of scope problems. You won’t be able to diagnose the problem. It can be difficult to diagnose scope problems when 1/8th-MOA click scopes start failing. This could be due to poor wind-reading or some other driver error. My experience has shown me that scopes can go wrong. Your optics could be the reason for your poor accuracy. Here are some symptoms of scope problems: Large shot-to–shot variance in Point of Impact with accurate loads.
2. Uneven tracking (vertical or horizontal).
3. Click inputs do not correspond to Change of Point Of Impact.
4. Inability to zero in a reasonable number of shots.
5. Unexpected changes in elevation click values (compared with previous distance come-ups).
6. Visible shift in the reticle at the center of view
7. Click-to-click “feel” may change or resist clicking; or it could be an uneven click-to-click feeling.
8. Inability to set parallax in order to achieve sharpness
9. Turrets and other controls feel loose or wobbly.
10. When the gun is moved, internal scope components rattle. Even the most expensive scopes can fail or malfunction, and this can happen without warning or for no apparent reason. Here are some signs you might be experiencing scope issues. 1. The click count has increased significantly from the zero-zero level at the known range.
2. You will notice a difference in the click “feel” when you rotate turrets or turrets may feel wobbly.
3. Inability to set Adjustable Obligation or side focus to achieve sharp target image.
4. The click value after elevation/windage changes has a different shot point of impact than the click value. When you dial 2 MOA “up”, you will see a 6 MOA increase in POI. Crazy Vertical Case Study: An expensive scope goes bad – A few seasons ago, this editor had an 8-25x50mm scope that was major-brand. How did I know that I had a problem with my scope? The first sign was a wild “drop down” flyer at a 600 yard match. After shooting a 2-target relay, I took a look over my targets. My first 5-shot group had five shots. They were all centered and shot in about 2.2?. It was pretty good. Everything worked perfectly. Then I turned my attention to the second target. My attention was drawn to four shots. They were all centered in the 10 Ring measuring approximately 2.4?. Then I saw the fifth shot. It was a good 18. It was low, straight down below the X. I mean straight down. If you draw a line from the center of X, it would almost pass through the fifth shot.
It was quite disconcerting. However, since I had never experienced any problems with this scope before, it was probably a load problem (too much powder?). It could have been driver error (maybe I flinched, yanked the trigger?). I decided to ignore the scope and not do anything about it, thinking that the problem was either me or the load.
However, things quickly went south at the next range session. I managed to get on the steel at 600 in three shots using my usual come-up for this distance. Everything went well. Then I switched to paper. A buddy was in the pits with his walkie-talkie. He radioed that he couldn’t see any bullet holes in the paper five times. My spotter stated that he believed the bullets were hitting in the dirt just below the paper. Okay, so we’ll increase POI 18 by adding 3 MOA (12 clicks). I should be in the middle of the paper. This didn’t work because the bullets were now hitting the berm above the target frame. The POI had changed by 48? (8 MOA). (And no, I didn’t click too far. I clicked slowly and counted each click loudly as I adjusted the elevation. Okay, I took 8 clicks to compensate. This should have been 2 MOA or 12. No joy. The POI dropped to 24? (4 MOA) and the POI moved 18? right, to the target’s edge. For the next 20 shots, we chased center trying to get the gun to zero at 600 yards. We never did. After using up a lot of ammo we gave up. Before we packed the gun for the return trip, I dialed back my 100-yard zero, which was my usual practice (it’s 47 clicks lower than the 600-yard zero). The “feel” of my elevation knob was not right. The clicks felt tight even though I was at the limit of my elevation (I have an +20 MOA scope mount). The clicks were very stiff and didn’t seem like they were moving at the right rate. I would have four to five clicks that were “bunched-up” with a lot resistance, then the next click would have almost zero resistance and seem to jump. It was almost like a spring that was jerking from tight to loose. I let one of my buddies adjust the elevation knob. He said, “That feels strange,” “The clicks aren’t consistent… it won’t want to move first, then it jumps too easily.” The scope was then packed up and shipped to the manufacturer. Was I hallucinating? Did driver error really cause my problem? There are many stories of men who sent scopes in to be repaired, only for them to be returned with a brief note saying “Scope passed inspection & function test 100%.” No repairs required. So, was my scope FUBAR? It was. The Repair Record indicated that almost all of the internal mechanicals had been repaired or replaced when the scope returned from the factory: “Replaced Adjustment Elevation, Replaced Adjustment Windage, Reworked Erector Systems; Reworked Selector. Reworked Parallax Controller. “Source of problem unknown, but I have a theory
My scope came with a slightly bent reticle from the factory. However, it had worked flawlessly for many years. I was able, for more than five years, to travel between 100-yard zero (or 600 yards) with perfect repeatability. That scope was reliable. Why did it fail? Side-loading on the Turrets is my theory. I used to keep the gun in a thick, soft case. I switched to an aluminum-sided, hard case with thick egg-crate foam. It took me a while to close the case. However, it was large enough to hold the gun. I believe the foam was not compressing sufficiently, which resulted in a side-load on windage turrets when the case was closed. This is my best guess. It may not be the true cause of the problem. This is just my best guess; it may not be the real problem.
