Any Reason why two scopes in a row would go bad

[grubbylabs]

Scope #1 Tasco, not sure what model but it is a 3X9
Scope #2 Vortex Crosfire
The rifle, Smith and Wesson M&P Sport AR-15

The first scope was not a surprise, it was an older Tasco that I got for free, The second scope was the Vortex, the cross hairs are now turned so the top of the windage element is at 11 O'clock position and the bottom at 5, and the elevation is about 8 and 2 respectably.

What I noticed was that last evening I was sighting in the Tasco and started out at 50 yards just to get it on paper, then moved it out to 75 yards. At 50 yards with wolf ammo it made a nice little group about 1" or so. At 75 yards no matter what ammo I used it was literally all over the paper.

So this afternoon I take my crosfire off my 300 win mag and mount it up and take it out. At first I thought I did not have the scope level, so I pulled out the screw driver and adjusted it. The next thing I now the whole reticle is turning back and forth so much I have no choice but to give up.

I was either shooting about 4" left with perfect elevation at 75 five yards and good groups or low and right several inches depending on which way the reticle was leaning.

Since the same ammo from last night was making good groups today with a different scope I assume the scope from last night (the Tasco) has a problem.

The Crosfire I just took of my 300 win which was shooting great, I just finished some load development with it a few weeks ago and the scope was just fine then.

 

[chaser_2332]

both just cheaper scopes, the crossfire comes from a great company but it is there lower end scope and seam to be hit or miss. Im pretty sure its still covered under vortex's warranty.

 

[M1key]

Tasco came loose? Wolf ammo

Vortex finally gave up? 300WM

Try a good quality, dedicated AR scope and better ammo...

Apart from that, it's difficult to say...

Good luck

M

 

[taliv]

300win mag has some recoil, you've no doubt noticed. it's not easy on scopes.


there are a couple things you could do to make them go bad. for example, overtightening your rings. if you tightened the rings to the point you can feel the magnification knob is harder to turn... you've gone WAY too far. another is mounting the scope's objective bell too close the barrel. keep in mind the barrel and the scope will flex so if you're just sliding a piece of paper between them or something and calling it good, they could still be touching under recoil. (edit: this doesn't appear to be your problem... i misread and now understand it worked fine on the 300 and the AR broke it?)

it's entirely likely your rings are not aligned or are not perfectly round (or at least, as round as the scope). it could be putting some tension on the scope that could easily damage it. many people lap their rings for this reason (though i prefer to just buy better rings)

 

[grubbylabs]

Ya that's the thing, the scope was fine on the 300, but went south on me on the AR. the are 1" rings and I only snugged them up good, I have heard lots of examples of people over doing it while tightening down the scope. the rings are also tall ones so there is plenty of clearance between the scope and rifle.

So either the 300 took out the vortex the last time I shot it, or something is not lined up right or out of round on the AR?

Oh and the factory ammo is just to get it on paper, I doubt its the problem. I figure it is pointless to start load development for the AR till I get the scope on paper and working correctly.

 

[jmr40]

Most scopes are designed to take recoil in one direction. While the rifle moves back in recoil, the scope tries to move foreward. Scopes are designed to handle this. On a semi you get the initial recoil, then a small amount of recoil moving in the opposite direction as the recoil spring slams the bolt forward as it loads another round in the chamber.

It is not a lot, and most decent scopes can handle it. But on a cheaper scope repeated use could be enough for them to fail, even on a light recoiling rifle. There are special scopes designed for air rifles. It is not uncommon for big game scopes that have been used on magnum bolt rifles to fail on air rifles for the same reason.

 

[06]

Would first suspect alignment, then over tightening, then--it was just time. Have had a Bushnell on a Winchester 100 for 45 years--still clear--still accurate.

 

[WALKERs210]

I had purchased one from Centerpoint, took to the range and at 100yds with full windage adjustment to the right I was still hitting 8yrs or more to the left. Took it back and got a second, it would not adjust for elevation. Learned that Centerpoint was not a scope I wanted.

 

[243winxb]

Keep the rings at least 1/4" away from the start of the bell, elevation adjustments & eye piece or power adjustment ring.

 

[SSgt0313]

Give Sight Mark a try

Give the Sight Mark Triple Duty M4 1-6x24 CDX (SM13021CDX) or one of the other variations. I use this for three gun and never had a problem yet. I also use Triple Duty 6-25x56 MDD (SM13019MDD) on my .300 WSM and love it. Have tree deer over 200 meters from a steady rest. http://www.sightmark.com/ I know you will not be disapointed with the quality or accuracy.

Sight Mark Pro Staff
Matthew Benack

 

[grubbylabs]

So after I buy a thousand dollar scope and have the same problem, what are you all going to suggest next?

A few of you have seen past the brand and have actually given me good advice and I thank you for that. However a few of you seem to think that the answer to a problem is to buy a better scope? I have a hard time thinking that a scope going from a heavy recoiling magnum rifle to a very light recoiling semi auto rifle is not up to the task. The Crosfire has spent well over a year and a few hundred rounds on top of the 300 win, with no signs of an issue.

I can't help but think their is something going on with the rings as a few of you have suggested. I remounted them and used lock tight this time.

 

[243winxb]

Bushnell in business for over 60 years

Had 1 scope go bad. Free replacement after 22 years of use. This was before the life time warrenty. The orginal warrenty run out after 20 years. Buy a Bushnell scope and use there life time warrenty.

Since 1984, the majority of our Bushnell sports optics products have been covered by a Limited Lifetime Warranty. Bushnell Outdoor Products guarantees those products to be free of defects in materials and workmanship for the lifetime of the original owner.

 

[grubbylabs]

Vortex's warranty is similar, except they don't care who bought the scope, if you have it and need warranty work, they will fix it.

 

[benzy2]

What rings did you use? We're they mounted to a different rifle when the scope was installed to them?

If it were me, I'd buy a quality set of rings, a non-China made scope, and follow the ring manufacturers recommendations for torque specs for mounting. I've had great luck with Larue and ADM for AR scope mounts. RRA makes a decent one piece cantilever mount that is affordable. For more standard style rings, I am a sucker for Burris Signature Zee rings, even if only using the non-offset inserts. I haven't heard of a single scope damaged by those rings and I also haven't heard of any scope slippage with them. Solid, safe rings.

Honestly, cheap rings are cheap for a reason. They often aren't perfectly true, or even close enough. If the bolt rifle 300 WM didn't have the screws for the bases drilled perfectly square you may be torquing the scope when swapping it to other rifles, assuming you did not loosen the rings to the scope when you moved it. In a highly unlikely situation, you AR upper may be out of spec and causing the bind.

I would point to the mounts and the scope quality. Non-China made scopes can be had for fractionally more than many Chinese optics. That price jump gains you exponentially better quality. Some good mounts and a good scope would be the easiest option to eliminate unknowns. Mounting procedure is another potential, but short of over torquing, most problems are solved with quality mounts. Call it getting stuck on price, but I find most issues clear up as quality gets better. I like Vortex but I'd much rather their Diamondback line than the Crossfire, even if I had to bump down a bit on features to afford it.

Since you will need a new scope anyways, I'd look into something like the Nikon Prostaff or Vortex Diamondback line for inexpensive yet better made optics. Add on either an RRA on piece mount or Burris Signature Zee rings and a riser and go from there. That should eliminate an equipment issue. Read up on torque for the rings. It doesn't take much. An inexpensive torque wrench can be had from harbor freight. While I wouldn't trust my life to its accuracy, it should get you pretty darn close for the $15-$20 they cost and it may save you another optic going bad.