Rifle Scopes Bender 5-25 Misbehaving!

[turbo54]

So my partner just got Field Firing Solutions, and we went went to the range to make sure our optics were tracking. We set up at 50 yards. I fired a group at 0moa, 33moa (almost top if first turn), and 64moa (almost top of 2nd turn).

My second group (33moa) actual POI was 35moa up, and my third group (64moa) was 66moa up from zero.

So, somewhere on the first turn, it gets 2moa ahead, but then tracks correctly. I was really surprised! I repeated the test 3 more times - no change. Called Bender, and they had me send it in.

Anyone experience something similar? I'm no scope engineer, but I have a decent understanding of what's inside them and how they work, and I find this very puzzling!

By the way, my partners Premier was dead nuts!

I'll update when I hear back from Bender!

 

[turbo54]

Re: Bender 5-25 Misbehaving!

Also, this really helps explain the strange dope I've had. The ammo chronos at 2655 (175smk in 308), but my observed trajectory takes 11.25moa @ 600 from a 100 yard zero, which back-caculates to ~2800fps. If you add the two extra moa to 11.25 to get 13.25 and then back calculate velocity, it comes to right about 2650!

Hearing my spotter call out "come down 1/2 mil!!" Has been a common scene!

I'm glad I found this issue - looking forward to getting scope back corrected!

 

[EventHorizon]

Re: Bender 5-25 Misbehaving!

Nice analysis!

Did you ever check your scope's tracking optically? As per Lindy's instructions?

How to check your scope's tracking optically

 

[turbo54]

Re: Bender 5-25 Misbehaving!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: EventHorizon</div><div class="ubbcode-body">Nice analysis!

Did you ever check your scope's tracking optically? As per Lindy's instructions?

How to check your scope's tracking optically </div></div>

Honestly,no. I thought that because I had spent a mint on a "Schmidt & Bender" scope, it must be A-OK. My partner got motivated to check because he spent $400 on a badass ballistics calculator. Honestly, I wasn't gonna be bothered checking mine, but because he set up the target and did all the work, all I had to do was put some cartridges in my rifle and shoot it, so I did.

Note: CHECK YOUR SCOPES!

For the last year my dope really had me scratching my head, but I never thought it could be the scope not tracking. Live and learn! Now I have to "unlearn" the fudge-factor-feel I've learned, and develop a new dope chart.

 

[Lowlight]

Re: Bender 5-25 Misbehaving!

Havent' we been caveating that in every discussion even remotely close to this, that without checking and calibrating both your scope, rifle and software, you are pretty much unsure of everything ?

Perfect example,

We say this stuff for a reason !

 

[turbo54]

Re: Bender 5-25 Misbehaving!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Havent' we been caveating that in every discussion even remotely close to this, that without checking and calibrating both your scope, rifle and software, you are pretty much unsure of everything ?

Perfect example,

We say this stuff for a reason ! </div></div>

Yep. If it's been said once here, it's been said a million times: Perform a tracking test on your scope!

This IS a perfect example! I wasted (not entirely, but you know what I mean) a year of "perfect practice" because I skipped this fundamental.

Just because you've got uber-glass, doesn't mean it is exempt!

 

[Lowlight]

Re: Bender 5-25 Misbehaving!

I received an issue GUNS magazine today in the mail, with an article showing the new Trijicon TARS and the author did a 7.75MOA Box test to demonstrate the accuracy of the adjustments.

Can we say, <span style="text-decoration: underline">complete waste of time</span> 7.75MOA will tell you nothing because you need to compound the errors, which is why we always say test the scope across 100% of the useable adjustment range of the scope. It matters and it makes a difference.

 

[flynlow3]

Re: Bender 5-25 Misbehaving!

Guess this next weekend I will be performing this test. Thinking something tracks well and knowing that it tracks well are two different things! And after reading this, I want the peice of mind of KNOWING my equiptment works as it should if there ever is a moment it has to count.

 

[turbo54]

Re: Bender 5-25 Misbehaving!

Update:

Bender was not able to fully reproduce the tracking issue. They also found the elevation to be a bit "advanced", but not the whole 2 moa I was seeing.

They did however, find a secondary issue with my reticle focus at high power, which they corrected with a new erector assembly. With the new erector, the scope now tracks dead nuts.

Now, do I drop $500 on new mrad turrets while it's there??? I think I oughtta!

I'm pleased with Benders service at this point. When my DPMS needed attention, it took 4 months. When my FN needed service, it took 5-6 weeks. The Bender was turned around in less than a week. Kudos.