Rifle Scope Not Holding Zero – How to Troubleshoot Rifle Scope

Rifle Scope Not Holding Zero – How to Troubleshoot Rifle Scope *The following rifle scope troubleshooting applies to most rifles. If you have a really odd-ball rifle or scope not covered by […]

Rifle Scope Not Holding Zero – How to Troubleshoot Rifle Scope

*The following rifle scope troubleshooting applies to most rifles. If you have a really odd-ball rifle or scope not covered by these steps, then tell us about it in the comments.

I read a post in a FB group for Mosin Nagant Modifications that described issues with the rifle scope not holding zero. While this relates to a modified Mosin Nagant rifle, the basics of how to troubleshoot a rifle scope that won’t hold zero are applicable for all rifles. Here is the initial post:

rifle scope won't hold zero - mosin nagant scoped rifle“…I shoot from a bipod and when I’m shooting my shots are all over the place. (my scope works perfectly, had it on my .223 and was shooting 2-3″ groups at 200 yards).
I was trying to zero my scope at 100 yards and it was 4″ low so I made the adjustment to come up 4″ and the next two shots I was 5″ high and then adjusted back down and was low again. Then my shots started going way off to the sides when I hadn’t made any adjustment to the windage on the scope.
I have an ati scope mount that’s bedded and used stainless steel screws. Checked them and they are nice and tight. Using the ProMag Archangel picatinny rail and a UTG heavy duty bipod. Mounts to the ProMag Archangel Opfor 9130 stock.”
He later said it is a Barska scope and he was shooting milsurp ammo (didn’t say what type).

Check these things so your rifle scope will hold zero:

*The links in this post take you to trusted online retailers where you can purchase these products and read more detailed info on them. 🙂

Mosin Nagant Archangel sniper build - ATN X-Sight Digital Day/Night scope

a)  Movement in the scope to scope mount connection. Make sure the scope rings are properly tightened and there is no play in the scope to rings or rings to rail connections. This is the most likely problem when a scope won’t hold zero, either because the parts fit poorly, were never tightened, or the scope rings worked loose as the rifle was shot repeatedly. I have had good luck with the very budget friendly Weaver Quad Lock scope rings for rail mounted scopes. A heavier duty budget option are the UTG Max Strength LE Grade Quick Detach Picatinny Scope Rings. You might also consider aligning and lapping the scope rings to be sure your scope is aligned perfectly within the mounts.

NRA Instructor Bob teaching the Gear Report team how to shoot better

NRA Instructor Bob teaching the Gear Report team how to shoot better

b) Shooter inconsistencies. You might have a tiny pre-recoil flinch throwing off your point of aim in the last milliseconds before the shot. You could have a heavy, rough trigger causing a bit of POA deflection as you squeeze it. You could be not pre-loading the bipod properly and that is throwing off shots. Who knows what else it could be? I prefer to blame the equipment any time the performance doesn’t match expectations. Heck, I won’t buy golf clubs without throwing

the driver just to be sure it feels right when tossing it in the water hazard… to join all the balls that I’ve put there. However, sometimes the shooter really is causing the problems, not the scope. Be honest in evaluating what you are doing before you rule out “operator error”. Most folks have never had detailed shooting instruction and, consequently, base their shooting methods on a combination of habit, observation of other shooters (who may be doing it wrong), and whatever their grandpa told them to do when they were 6. Consider getting high quality shooting instruction to make it more likely that you are doing it right.

 
c) Scope failing under heavy recoil. I had an old Center Point scope that I used a LOT on .223 rifles for testing and it was fantastic for that purpose. Things changed when I put it on my Mosin “Sniper” build and it won’t hold zero. Period. Some scopes simply aren’t built with strong enough parts to handle the energy imparted on them when the rifle is fired. This is why some scopes are only rated for the very low recoil .22 lr ammunition… anything more powerful is likely to break something within the scope. Be sure your scope is rated for the cartridge that you will shoot. 
 
7.62x39 ammod) Barrel harmonics and the Tensioning Block. If the barrel touches the stock or not will vary by rifle make and model. In the example above, the ProMag Archangel Opfor 9130 stock free floats the barrel by default, but also comes with a small “tensioning block”. If installation of the barreled action in the stock throws off your shots, try installing the tensioning block and playing with amount of tension it puts on the barrel. This process can be tedious, but can really help if your harmonics are out of whack. This is less likely on a rifle in it’s factory stock, more likely after a rifle stock replacement. Most stocks don’t have a “tensioning block”, but you can create pressure, or tension, on the barrel by inserting cork between the stock and barrel, wrapping the barrel in something that will deaden the harmonics, etc.
 
e) Ammo inconsistencies. Before you put a lot of time and $ into troubleshooting the rifle, buy or trade a friend for 20 rounds of a different type or brand and see if you get the same results. Wouldn’t you feel silly if you spent time and money working on your rifle and scope, but eventually figured out that it was a bad batch of ammo? For a real life example, see how I struggled with the new T/C Compass hunting rifle with surplus Greek HXP .30-06 ammo (review).
 
rifle scope won't hold zero - wheeler rifle bedding kitf) Movement of the barreled action in the stock. It may be time to bed the rifle receiver to the stock to be sure they don’t move in relation to each other during the shot. Bedding can involve applying a layer of thick liquid like epoxy that will cure rigidly in the exact shapes of the stock cavity and rifle receiver, installing metal bedding pillars to support the action, or both. Eliminating the relative motion between the stock and the rifle action is considered by many to be a key component in unlocking the accuracy potential of any rifle.
rifle scope won't hold zero - scope adjustment testg) Inconsistent scope adjustment mechanism. All scopes are not created equal. A big selling point on higher priced scopes like those from NightForce, Leupold & Stevens, Steiner Optics, US Optics, Swarovski, Trijicon, etc. is a more durable and precise adjustment mechanism. Gear Report writer Jason has a very basic test to quickly weed out the mass of pretenders from the scopes that have more robust, repeatable adjustments (the numbers in the EZ2C Targets graphic show the progression of shot POIs listed below):
  1. With the rifle firmly supported shoot an initial group of shots to establish point of impact.
  2. Turn the windage adjustment 16 clicks clockwise and shoot at same point of aim.
  3. Turn the elevation adjustment 16 clicks clockwise and shoot at same point of aim.
  4. Turn the windage adjustment 32 clicks counter-clockwise and shoot at same point of aim.
  5. Turn the elevation adjustment 32 clicks counter-clockwise and shoot at same point of aim.
  6. Turn the windage adjustment 16 clicks clockwise and shoot at same point of aim.
  7. Turn the elevation adjustment 16 clicks clockwise and shoot at same point of aim.

If the 7th shot hits the same point as the first shot, then the elevation and windage tracking on the scope are sound.
However, if your 7th shot does NOT have the same point of impact as the first shot, then your scope’s elevation and windage adjustments are less than completely reliable.

If none of that helps?

Obviously it is possessed. Sell the rifle and scope and buy a new one.

About Jeff

Jeff is the Editor in Chief of Gear Report and a National Shooting Sports Foundation Media member. He reports on the outdoor industry, reviews gear for camping, hiking, shooting, hunting, paddling, backpacking and other active pursuits. A USAF veteran, Jeff earned a MBA in Marketing and Health Services. He specializes in consultative selling and internet marketing. As the VP of BD & Marketing, Jeff provides sales and marketing leadership to MGECOM, Inc. and helps http://MGECOM.com acquire new clients in need of solutions for online merchants in need of Affiliate Marketing program management. Jeff founded and manages Cress Sales & Marketing LLC, offering online sales and marketing consulting and services to online merchants and service providers.