Home Forums Hunting & Shooting Hunting Optics Scope Failures: Sudden or Gradual?

I was thinking about this topic as I put about 100 rounds of 375 H&H through my gun in the last couple of weeks in two range sessions. The gun isn't particularly heavy, so the recoil is "up there". I have a system that allows me to put different scopes on but I have a one or two I use most often, so one or two have seen quite a bit of 375 H&H, and 300 Weatherby action - probably hundreds of rounds between load development, hunting, etc.

After 50+ years of hunting and shooting, I've never had a scope fail. I'm not a turret twister. I've got a variety of mid-range brands and they've always done their job. Now, the internet has taught (!) me I'm clearly in the minority and just downright lucky. So, for those of you who have had failures, how did they manifest themselves? Gradual decay or "Bang" it's dead?

The only "sudden" failure I have had was a Pecar 4x which had a broken reticle...sent it to Harry Gackle who repaired the scope, I have sent a couple to Leupold for cleaning and servicing, one to Premier Reticles for modification, and a couple of 6.5-20 Leupold that I didn't trust went down the track to new owners.

That is the extent of any "problems" I have had with scopes.

Both. One gradually loosened up as evidenced by the groups from a standard load in a reliable rifle getting larger, and then a scope swap shrinking the groups. Another started to need its side focus adjusted after each shot. Another went bang with its side focus giving up all at once.

I have boxes of take off scopes. I don't count them.

Dead on arrival.....In 1995 I received a B&L 4x12x40 AO Elite 3000 for $270 that had a misregistration of lenses and cannot be used much above 4X. I never sent it back.

Sudden death....In 2002 I had a $200 10x40x50 Tasco World class plus crack up. Replacement was free, but took 18 months.

Sudden death.....n 2005 I had an old Vari Xii 2x7 Leupold shake loose the reticle on a diving board of a slim cantilever weaver base for a Mosin made from AR15 riser. That was my fault, but Leupold sent me a new scope, a VX1 2x7

Dead on arrival....In ~ 2010 I received a $200 Super Sniper 20X that had a misregistration of lenses and cannot be used for anything. I never sent it back.

I have had multiple types of scope failures over the years:

Two scopes, a Zeiss and a Schmidt and Bender, had a bunch of black specs appear on the internal lenses. In both cases, it happened in the first 30 rounds.

One Swarovski Z5 had an erector problem. It was gradual, over the course of 50 rounds or so. A proven five shots in .500" rifle and load combination became a 1.5" rifle and load combination. Swapped for a proven NF scope and the groups dropped back to .500".

Then there were my newer production Leupold issues that started about ten years ago. I have had six or so scopes fail to retain zero during that time. About half were a gradual opening of groups and the other half happened suddenly. One minute the rifle is shooting in the .400"s, the next group is three inches. Often, with the catastrophic failures, the POI will bounce around in a back and forth fashion. You may have two bullets hit fairly close to each other, and two bullets hit three or four inches away.

I think there are a lot of scopes out there that probably don't hold their POI as well as their owners think they do because a lot of folks are perfectly happy with rifles that shoot 1.000" to 2.000" groups. If a scope has .500" of slop in the erector, you may never know if you are accustomed to shooting 1.500" groups. The rifle might be capable of better, but the owner may never know it.

Having said that, if you have been using 'Brand X' scopes for years and never had an issue, then you are obviously using them within their design parameters and should carry on. If you are like me, you may need something that holds its POI better. Fortunately, both types of scopes are made every day.

I had lots of failures. But it was sort of not fair. I was using a Freedom Arms .454. Some would not last for six shots. Some would start with the field of view shrinking.
Some would have seals start squeezing out.

On a .223 with a heavy 26" barrel the reticle started rotating in an 8-32X Burris. I returned it for service. When it came back I took the cap off to adjust the windage and
there was nothing there. Just a hole into the center of the scope. They repaired it. After some more rounds the groups opened up. I installed a different scope.
The next five shot group was .312".

On a lightweight .257 my Swarovski z5 failed from the very first adjustment. But if finally settled in. Then over the next two years the erector had to be replace twice.

They start dying the minute the first shot is taken. If they have a design flaw they may last a few boxes of bullets, after that who knows.

I had a scope whose reticle suddenly failed - after the shot there was just a hair, not a crosshair. I had another scope , a variable, which I was out hunting with, and when I went to take a shot it was out of focus - way out of focus - and when I adjusted the magnification and pointed it up and down it dropped in and out of focus. Clearly something had come adrift inside.

Another scope worked fine for years, until I was at the range one day sighting in for a new load and noticed that the POI didn't seem to be following the dials accurately. Not being a scope I twiddled the dials on, that scope may have had that problem for a while, and it may well have continued to function, as long as I got it sighted in and left it there, but I lost confidence in it.



I think there are also those who sight in and check groups on maximum magnification on their SFP variables, and never check to see what sort of POI shift they might get if they change the magnification

And that right there is at the very foundation of shooting.


Confidence in one's gear.

I had one right out of the box that would move three inches horizontal when switched from 10X down to 2 1/2X. I used it for a whole season to take a doe and a buck.

I had a brand new 2 x 7 Redfield Iluminator mounted on my new 35 Whelen that I had shot a few times to sight in. First deer I shot at the horizontal cross hair broke completely in 2. Sent if back to Redfield and they wanted me to apply it and as much as I paid for it toward one of their cheaper lines of scopes. They eventually fixed it and it has been on several lesser recoiling rifles and held up well.

I have had failures, never had a recital break but have had scopes that did work all of a sudden shift point of impact or aim. I will check the mounts, and if it does not help than it's the scope. Always with a rifle I know and have shot. Only a couple, but it does happen.

I had a Bausch and Lomb on a Husqvarna 30.06 when a splendid whitetail buck came in on a run, stopped and looked behind it. I believe it was spooked by other hunters. But no matter, I settled the crosshairs on its chest and squeezed off a shot. The buck dropped where it stood, maybe 50 yards away tops. I got over to it, and after counting points, looked for my bullet hole. There was none in the chest...then I noticed one through the neck...just beneath the skull!

I had sighted the rifle in a week or so before, and I felt good on the shot, though he did catch me by surprise. I wiggled the scope, seemed tight. Then I looked through it. Instead of the crosshairs being horizontal and vertical, they now formed an X!

That was the only time I've had difficulty short of some real cheapies that I knew I would before I started.

Tasco world class.
Trying to remove the horizontal adjustment cover,
the whole turret came off.

Chitt canned it, may have still worked, but why bother.

This evening I remember some Simmons. The first time I adjusted the magnification everything went blurry. I called and asked if I could return it and pay an upgrade to the next level. They cooperated. This happened four times. On the last time I never opened the scope package. I sold it as new in the box with all papers.

I've now had 18 different brands (not individual scopes) fail on my rifles. Sometimes it's sudden, as in they don't work right out of the box, sometimes it's gradual, and sometimes they've taken a hell of a beating before giving up. Had one that was my test-scope for harder kicking rifles, anything from a .338 magnum up to .40+, for a number of years, before the reticle broke on, of all things, a single-shot .30-40 Krag.

That was a clear case of long-term abuse, but others have obviously been failures of design and/or build. Have had two scopes spontaneously unscrew their objective lenses--which were NOT adjustable objectives. Had another that resulted in groups about an inch high and 12-15 inches wide, and another quit working on a .17 HMR.

Recently had one that many "woods" hunters might not have recognized was going bad--and it took a while for me. It was on my very accurate Nosler Liberty rifle in 26 Nosler, and every time I took the rifle to the range the 100-yard POI had shifted a little, usually less than an inch. The adjustments still worked perfectly, so it would only take a shot to re-zero, but eventually the groups started getting slightly larger, and I finally realized what was happening. Put an absolutely reliable older scope on the rifle, and it went back to shooting groups well under an inch, and POI held exactly in the same place. But I doubt if it would have caused any problem on, say, a .308 used for shooting deer at less than 300 yards.

Mine was subtle. A rifle was starting to shoot 1” where it previously shot .6-.7” groups then it became the occasional 2” group. I went through a lot of ammo chasing that. Finally put another scope on and it instantly shot better.

Anything mechanical is one step closer to failure with every cycle. Just don’t know how many cycles it will last! Happy Trails

John, you are scaring the hell out of me! One of my fears is a wasted hunt or a wounded animal. Maybe I need two scopes atop my rifle and then compare the two. Or maybe it should be three.

How effective are laser bore sighters for checking the scope from time to time? Are they repeatable enough?

Not JB, but in my experience, no. My "failure" was so subtle you'd never know if you had the laser in slightly canted or if the scope was off just a touch. Perhaps there is a better laser boresight system than I have though.