Most definitive way to determine scope failure

millerkiller77

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Just that. What's the absolute most reliable way to pinpoint scope failure as the culprit for accuracy issues? Box test?
I've got a 300wsm on a M70 action, 26" proof sendero barrel. Less than 70 rounds through the rifle. I checked the action screws, base, scope mount, barrel clearance, all good. Bore scope shows nothing remarkable in the barrel, no baffle strikes, the chamber is a little rough, but no problems cycling ammunition or spent cases. Spent brass looks normal, no indications of problems with the brass.
New factory loaded Norma 180 gr ammo , all from the same lot.
Scope is a Leupold VX-6HD, purchased new and only mounted to this rifle. The scope has already been warranty serviced by Leupold once after less than 30 rounds for a completely seperate issue and all the internals passed inspection. New mounts, remount the scope and it's a shit show all over again.
Group one is after I've made rough adjustments just to get it on paper. Looks good and what I'd expect this rifle to shoot, I make my final adjustments and shoot group two. It's off by 3/4 moa for some reason, no big deal, I dial 3/4 left (elevation wasnt touched)and put the rifle on the rack to cool.
Group three has me scratching my head. I shoot six rounds , make the corrections on the windage (not elevation) and let the rifle cool again.
Group four goes from one extreme to the other, I dialed 1/2 moa left , let the rifle cool.
Group 5 is when I called it quits, at this point I'm so frustrated that there is no point in continuing.
I'm open to questions or suggestions about something I may have missed, but I'm leaning towards a defective scope at this point.
First pic is from my session yesterday, second is from Aug 2023 using the same scope and ammo before I sent it in for warranty. I was able to get four rounds before it started spraying the target like a shotgun, that ended up being a mounting issue causing the need for Leupold service.
Screenshot_20240103_141248.jpg
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I don’t know what the deal is. I have 20+ leupold scopes. This is the only one that I’ve had troubles with.
 
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You can perform a box test if you strap the rifle/scope down. I assume rings and base were torqued to spec?

I loved my VX6HD, but this is what I was afraid of so I sold it off for Nightforce. I suggest you do the same. Or Trijicon. The new Maven RS1.2's are looking fairly reliable so far.

I think enough people are starting to realize that Vortex and Leupold warranties are fine for binos/spotters, but a rifle scope HAS TO BE RELIABLE. A warranty won't make up for missing your once in a lifetime mountain goat (*cough cough Fresh Tracks episode*).
 
Any chance you can swap another scope off another gun? Probably not the answer you want to hear but that makes it as black and white as it can be.

I recently sighted in a Mark V and had similar groups. Soft point bullets were the culprit, my gun didn’t like it. Switched to polymer tips and all was okay. I assume the 70 rounds had non soft points as well?
 
You can perform a box test if you strap the rifle/scope down. I assume rings and base were torqued to spec?

I loved my VX6HD, but this is what I was afraid of so I sold it off for Nightforce. I suggest you do the same. Or Trijicon. The new Maven RS1.2's are looking fairly reliable so far.

I think enough people are starting to realize that Vortex and Leupold warranties are fine for binos/spotters, but a rifle scope HAS TO BE RELIABLE. A warranty won't make up for missing your once in a lifetime mountain goat (*cough cough Fresh Tracks episode*).
Definitely torqued to spec, and verified again this morning.
 
Any chance you can swap another scope off another gun? Probably not the answer you want to hear but that makes it as black and white as it can be.

I recently sighted in a Mark V and had similar groups. Soft point bullets were the culprit, my gun didn’t like it. Switched to polymer tips and all was okay. I assume the 70 rounds had non soft points as well?
I could swap it with another scope I guess. I've already invested over $600 into 3 different scope mounts for this gun and now the reciever is tapped for larger diameter screw, so I'm kinda committed to sticking with a 34mm tube. That's going to limit me on optics options

All 70 rounds were the Norma tipped Bond Strike long range. I picked up 26 boxes of the same lot number dedicated to this rifle since they shot well out of 3 other rifles in the same caliber and make for excellent brass to reload.
 
I could swap it with another scope I guess. I've already invested over $600 into 3 different scope mounts for this gun and now the reciever is tapped for larger diameter screw, so I'm kinda committed to sticking with a 34mm tube. That's going to limit me on optics options

All 70 rounds were the Norma tipped Bond Strike long range. I picked up 26 boxes of the same lot number dedicated to this rifle since they shot well out of 3 other rifles in the same caliber and make for excellent brass to reload.
Ah shoot, I would have offered to try my scope but mine is 30mm. Well that being said, I would try a different brand of ammo first before I commit to swapping a scope. Hopefully you got a buddy that has the same cartridge you do.
 
Just brainstorming.

Parallax issue? I had to send a Nightforce back because when the image was in focus parallax was bad, and when parallax was eliminated the image was out of focus.

Do you have a bore sighter you can use to watch through the scope as you dial a box test to see if it’s tracking properly?
 
Just brainstorming.

Parallax issue? I had to send a Nightforce back because when the image was in focus parallax was bad, and when parallax was eliminated the image was out of focus.

Do you have a bore sighter you can use to watch through the scope as you dial a box test to see if it’s tracking properly?
I don't think it's a parallax issue, and yes I have a borescope but I doubt I can see the laser past 20 yards in daylight.
 
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