Has Anyone Ever Had A Scope That Lost Zero?

[Turkeytider]

If the answer to the title question is " Yes ", then how did you first know something was amiss? What were the symptoms? How did you verify it and was that the end of the scope? Thanks.

[25-204]

Yes about the fifth round through my 35 Whelen everything went fuzzy and you could here things rattling inside. I've had scopes start putting shots in big groups but usually turns out to be a loose base or ring.

[Dave Hoback]

Never have, I’ve been very lucky with all my glass. Granted, I haven’t had several dozen like some of you. While I’ve handled & used countless scopes through friends & work for a time, I myself have only owned a handful scopes. And to be fair, I haven’t used any of mine to the extent of some. That said, from the combo package 3-9x40 Simmons on my first Savage, to the first “decent” scope I pitched many years ago, a Nikon Monarch 4-16x50 SF, and the newer scopes I’ve owned in recent years, none have failed me.

That said, any scope can & does fail to hold zero. Be it a the scope itself failing, something the mounting coming loose or a different load of ammunition being used. Why, even temperature can have a big impact on zero.

[J.Baker]

I've had a few scopes go south on me over the years. Had a few cheap Tasco's on air rifles as a kid that had the crosshairs come loose and rather than being oriented like a + they rotated and were more like an X and would rotate to a different position every time I fired a shot.

Around the 2006-07 timeframe I had a Mueller scope that had a seal go bad. What was a good clear optic one deer season turned into a very milky or soap scummy picture when looking through when I pulled it out of the safe the following hunting season. Basically a seal failed and allowed oxygen/moisture into the internals. This type of failure isn't nearly as common today as it was back in the earlier days of optics as we have far better manufacturing methods and the seals are made of much more durable materials that are far less prone to drying out and cracking over time.

About 10-11 years ago I had a Weaver Classic V 6-24x that stopped holding zero after about 3 years. Gun went from being a 3/4" or better to shooting 4-5" patterns at 100 yards which is what raised my suspicions. This is probably the most common failure most will encounter, and usually has to do with a weakened or defective erector spring which is the spring that keeps tension on the internal tube in the scope opposite your turrets. Most are located at the 7 o`clock position when viewed from the rear of the scope and push the erector assembly up and sideways into the windage and elevation turret abutments. Insufficient tension on this spring allows the erector assembly to jump and move around a bit from the recoil causing the zero to shift.

As for how to check/verify in a case like this, using a collimator-type bore sighter is the best way. https://www.savageshooters.com/content.php?401-Bushnell-Professional-Bore-Sighter

I also had a Leupold FX-III 6x42 that had bad mechanicals (turrets). Adjustments when trying to zero were very erratic and inconsistent which made things extremely frustrating. Sometimes an adjustment would move 2-3x further than it should have, other times could dial in 8-10 clicks and it would barely move the POI at all. Sent it back to Leupold and they got it sorted out, but they never said what the actual issue was that caused it.

[Turkeytider]

I checked the tracking with a box test and it seemed to be fine. Up, over, down and back to the original aiming point. If the scope lost zero, or had any other mechanical issue, would it still pass this test?

[Turkeytider]

MANY thanks for the responses!
Good news!! Verified original zeroes on a couple of previously dependable loads ( 69 and 75 grain ). Sub-MOA groups at 100. At 500, back to " normal " frequency of hits. Have no idea what the hell was going on yesterday, but in thinking about it, I do recall a bit of swirling breezes. It is , after all, a .223 and I didn`t make any changes because I didn`t think it significant at the time. COULD be. Anyway, scope ain`t broke! Thanks again, guys!

[charlie b]

Glad to hear. Yep, the gusting, swirling stuff is tough with lighter bullets at range. I was kinda shocked how much they will drift past 500yd.

Only two scopes failed me. One the crosshair broke (Tasco or Bushnell, don't remember) and another the elevation turret knob stopped doing anything. It still held where it was, just didn't move the reticle anymore. Yes, took a few rounds before I figured that one out. I think that was a Bushnell.

[godale316]

ihad one that just went the color purple on me

[shotar1]

Yes, I had a Leupold vari X ii that just plain wore out. Indication was that it simply started grouping all over the place. Filled out form, sent to Leupold and in 2 weeks, I had a new scope in my mailbox. They couldn't fix it so sent me the current comparable model.