What Went Wrong With My Scope ?

[wedgy]

Last time I shot my 6.5x47 was at 1,400 yards and everything was good if the wind didn't shift. I took the gun out yesterday and shot at 100 yards and the 1st shot was ~1.5 inches low at 7 o'clock,(WHAT ?? this gun is my go to, always solid hunting rifle) 2nd shot about another inch the same direction, 3rd shot even more left. Something is loose, check everything and it is tight. The next 3 shots go into a group that is more characteristic of the rifle. That was the end of that session as that was the last of the ammo I had, same batch, same brass, bullets, powder,, proven load, etc. I assume something came loose internally with all the dialing and it did not return to zero. That was all the ammo I had so that was where it ended. I've seen scopes loose their zero but never walk that far off then settle.
How should I proceed ? Scope is a March 2.5-25x52 and had been solid until now.

 

[JEFFPPC]

Put another scope on, see if the problem goes away. Did you use Iosso or JB , could take 6 or so rounds to settle down. I am looking at the sequence of you shots.

 

[gambleone]

Load 5 more of same load & shoot at 100, see what it shows.

 

[wedgy]

Put another scope on, see if the problem goes away. Did you use Iosso or JB , could take 6 or so rounds to settle down. I am looking at the sequence of you shots.

No cleaning since I shot the gun last time ~2 weeks ago, I run a patch with Boretech carbon solvent down the throat but it doesn't effect more cold bore shot on the next outing. I won't have time to shoot it again for a while as I have muzzleloader tag next weekend.

 

[Turbulent Turtle]

There's a lot of information missing. You said the last shooting session was at 1400 yards. When you shot at 100 yards, did you wind down from 1400 or did you go to the 0-set? Also, did you set the windage back to eliminate spindrift for 1400 yards?

 

[wedgy]

There's a lot of information missing. You said the last shooting session was at 1400 yards. When you shot at 100 yards, did you wind down from 1400 or did you go to the 0-set? Also, did you set the windage back to eliminate spindrift for 1400 yards?

I had dialed ~45 MOA to get to 1,400 yards , wind was 3 o'clock and countered the spin drift but still had 3.25 right. I dialed both back to zero and put the gun away 2 weeks ago then shot it yesterday at 100 yards and that is the shot sequence from #1 to #6 in the picture. It did not get dropped or anything like that.
I have had a scope loose zero before but not this far and it didn't walk away like this one did.

 

[CJ6]

It could be "settling" after all the dialing.

 

[Turbulent Turtle]

I had dialed ~45 MOA to get to 1,400 yards , wind was 3 o'clock and countered the spin drift but still had 3.25 right. I dialed both back to zero and put the gun away 2 weeks ago then shot it yesterday at 100 yards and that is the shot sequence from #1 to #6 in the picture. It did not get dropped or anything like that.
I have had a scope loose zero before but not this far and it didn't walk away like this one did.

Understood, somewhat. Did you use the 0-set feature, or did you dial down about 45MOA from the last 1400?

Since the rifle is grouping nicely after shot 3, I seriously doubt there is anything wrong with the riflescope. I would look at the dialing numbers and so on. I spend a lot of time at 1000 yards in F-class and when I do load development and other things at 100 yards, I just use a tall target and aim at the bottom, I do detect the spindrift deviation, about an inch left at 100 yards from the 1000-yard setting.

I also think there may be some cold-bore stuff going on.

I have my 0-set at 600 yards so that I don't have to count the clicks from 1000 yards.

 

[wedgy]

Understood, somewhat. Did you use the 0-set feature, or did you dial down about 45MOA from the last 1400?

Since the rifle is grouping nicely after shot 3, I seriously doubt there is anything wrong with the riflescope. I would look at the dialing numbers and so on. I spend a lot of time at 1000 yards in F-class and when I do load development and other things at 100 yards, I just use a tall target and aim at the bottom, I do detect the spindrift deviation, about an inch left at 100 yards from the 1000-yard setting.

I also think there may be some cold-bore stuff going on.

I have my 0-set at 600 yards so that I don't have to count the clicks from 1000 yards.

Yes, March has the easiest zero stop there is and it has always returned to the same 100 yard zero(both on the turret and point of impact) in the past when shooting out to long ranges.
Yes, I returned the windage to zero also.
Cold bore is always in the pattern unless I scrub the barrel to bare metal, temp was similar to other days not having this issue, I shoot H4350 so I don't really have issues with heat.
this is by far the worst group this gun has ever shot since load development and the fact that it is way off my established zero and that it progressively walked away from the zero is something I have never seen.

 

[X-Caveman]

Scope checker.

 

[mikecr]

I had similar happening with a NF NXS.
I was able to put another NXS on, which I used as a 'standard' scope, and had no issue with the standard.
Sent the offending scope to NF describing the problem.
They returned the scope 2 days later with a note that there was a lens bedding issue (which they fixed).
Never had a problem with it again.

It's good to have & hang onto a scope which you know to be flawless, just for load development and troubleshooting.

 

[wedgy]

I have had two March scopes of this model that had the reticle come loose and turn so it is obviously tilted when the rifle is level, both on big braked .338's. Each one took about 6 weeks to japan and back and came with a note that said the reticle came unglued and they reglued it and an apology for the inconvenience. This one is on a little 6.5 so I don't think it's recoil related. I have a hunt next weekend and I was having issues working a load for my 6.5 Sherman Max but I ended up getting it verified out to the same 1,400 yard target. I took the 6.5x47 in case I had to take it and not the Sherman, which wears the same 2.5-25x52 March scope, no issues so far. I will have to sort it out when I get back but the 6.5x47 has been rock solid and I kind of suspect the scope more than the rifle.

 

[Turbulent Turtle]

I think it's refreshing that a company acknowledges there was a problem with their product, fixes the issue and apologizes for the inconvenience. Very refreshing.

I guess I'm not very smart, so I apologize in advance for my errant thinking. You said that you checked that everything was tight after the first 3 wider shots. Then you proceeded to shoot a nice little tight group with the next 3 shots. One could almost think that the process of checking for tightness silently fixed the problem, but the zero point moved a bit.

 

[wedgy]

You said that you checked that everything was tight after the first 3 wider shots. Then you proceeded to shoot a nice little tight group with the next 3 shots. One could almost think that the process of checking for tightness silently fixed the problem, but the zero point moved a bit.

I have seen small zero shifts but nothing like this, especially as I was shooting it was walking. someone mentioned have a solid scope to check the rifle, but this is my solid rifle that I would use to check a scope. LOL that is why I am leaning towards the scope being at fault. My question I guess would be what is the part of the scope internals that go bad and would show a movement like this and will it move again ? I don't know enough about the internals to make an informed guess and was hoping some would.

 

[Turbulent Turtle]

Let me preface this by saying that I do not work for March, nor do I sell their scopes or any other riflescopes for that matter. I'm an old IT guy specializing in data bases and older computer languages.

My strategy at this point, would be to load some more of that exact same ammo, remove and reinstall and tighten the ringed scope to the recommneded torque values, and go shoot a group of 3 at 100 yards. If it groups as well as your shots 4-6, I would then crank the elevation knob for 45 MOA and bring it back down to the exact same spot, and shot another 3-round group. If it groups properly again, I would confirm my zero at 100 yards and rely on the dope I have.

If it doesn't group well, I would contact Deon and discuss the issue with them.

I'm happy to discuss how the internals work. The test above is a way to eliminate the scope was the issue.