how do you know if a scopes gone bad?

[mattri]

Last time I took my .270 to the range it shot .72 at 100 yards. Biggest group of the day was about 2".

Today I couldn't even hit the box the target was on.

Same rifle
Same scope
Same range
Same rest
Same ammo
Same shooter
Same conditions

All mounting hardware is tight, action barrel etc look fine.
Was planning to bring it in to 50 yrds and see what's up. Any suggestions?

 

[Thorbird]

I'm sure you have already done this, but recheck all the screws on the rings to start with. Did you use a scope level to mount the scope? I take it it received no bumps in between. You might try to see how it tracks by shooting a 4 corner box?

I know you have probably thought about these things but that is about all I can think of right now.

 

[markr]

Generally speaking, they develop a problem communicating with you, then sometimes they start to get in trouble and even get locked up...wait a minute, wrong answer ;D

Do as thorbird said and or replace with a known good scope.
Mark

 

[k80skeet]

Easy way to check it out is to install another scope zero it shoot the rifle and see if it groups. If it groups then you have learn that it is not the rifle. Reinstall the other scope and try it again. If it does the samething it did before (group one time and not the next) you can pretty much figure the problem is in the scope.

 

[therifler]

Take the bolt out of the gun set the gun on your sand bags or rest what ever the case might be . Look through the bore and line the bore up with the target . Now make sure you don't bump the gun look through the scope and see if it is on the target . If it is not you got a problem chances are you bumped the scope . Making sure the bore stays on the target adjust your scope to the center of the target . align the bore again and see how close you are to the target . Repeat this till you have the scope aligned with the target . Then try shooting again . If you cannot adjust the scope or it does not move it is a bad scope .

 

[fdshuster]

michael: I've only had a few scope failures over many years. The first was a 4-12x Redfield (Denver mfg) that developed a rattle when shaken, definitely a failure & repaired bt Redfield. Another, a 12x Redfield (Denver) side focus, would not hold windage adjustments. 10 clicks one time would equal 2 1/4" of movement, next time 10 would produce 1 1/2" inches. Front objective bell came lose on the main tube. Repaired by "Iron Sight", Tulsa OK. A lot of internal failures are related to the erector tube, very common for them to "break lose" from their internal mounts, especially common with the "big kickers". Quickest way to check is simply as mentioned above: swap with a known good one.

 

[therifler]

Frank why swap scopes if he can't hit the target ? He does not know if the scope is not tracking he said he could not hit the target .If you align the the bore with something and then adjust your scope to that object you will know if the scope is tracking .You can do this from your patio or garage or across the living room if need be without firing a shot . If it is not holding point of impact you find out when you shoot it .Of coarse all these suggestions are great. But did anyone ask what kind of scope it is ?

 

[mikecr]

I follow k80skeet's thinkin and have an extra scope in the safe which I know to be good. It was with this that I finally found a sneaky POA issue with another scope that turned out to be a lens bedding issue.

My groups would intermittantly wonder, until I set my 'standard' scope on the gun. Then it would shoot great for weeks.
Both were NXS, and they fixed the problem scope immediately on discovery.

So if you happen across a scope that turns out to be a real shooter, even if you hate it for some reason, hang on to it for validating others down the road.

 

[fdshuster]

michael: A classic example of "why swap scopes" can apply when trying to verify a scope failure. The before mentioned 12x Redfield would not hold any consistant adjustment settings, especially in windage, but also with some vertical "wondering". Removed the scope and replaced it with a 6.5-20x Leupold that I know to be trouble-free. Problem went away. Re-mounted the Redfield and the problem returned. Yes, I realize there are many different types of causes of failures, but I'll let the repair facility determine that, all I am interested in is the answer to the question, " Is there a problem with this scope"?

 

[therifler]

Hi , Frank what if you don't have another scope ?

 

[fdshuster]

The original question was (I'm paraphrazing here), "How do you know if a scope has failed"? I responded with the system I've been using, on the rare occassion the problem crops up, by saying I mount a scope of known reliability, and am able to isolate the problem, with the least amount of effort. With 18 rifles, each with a high quality scope, plus a few spares, the availability of a "test" scope has not been a problem. Been involved in precision shooting/reloading since 1960 ( the Denver Redfields made in the early 1960's), so like anyone else, tend to "accmulate things". Good quality scopes are available (Bushnell comes to mind), and I have an old Weaver 6x that cost $125 when new, and surprisingly high quality. Both examples of scopes that can be obtained with a minimum $$$$ investment, but are invaluable when needed as spares, and for testing. Not any different from someone going on an expensive hunting trip (prairie dogs), and only taking one rifle/scope with them. Always nice to have a back-up. Maybe someone else can come up with a "fix" when another scope is not available.

 

[therifler]

Your reasoning makes sense to me Frank . I cannot afford to take one off my rilfes I shoot all winter 600yd. IBS.