Reticle Perpendicularity

[xarcher]

Have been reading articles in this forum about checking reticle perpenpenicularity with the long plumb line method. So I tried this with my model 700 in 30.06 at the range yesterday. I zeroed it at 100 yards then turned up 15MOA and got 2 holes almost on top of each other at 3/4 inch to the right. With a 100 yard zero, 15 MOA translates to about 550 yards and at that distance the bullet would be expected to hit a little over 4 inches to the right.

But I usually have a 300 yard zero on that gun and the adjustment to get to 550 yards from there is 7 MOA or roughly half of what it would take from a 100 yard zero. And given the perpendicularity offset measured above, that tranlates to 3/8 inch to the right for 7 MOA.

So here is my question. If I zero my gun at 300 yards instead of 100 yards, wouldn't the offset by 1/2 as much at 550 since the adjustment is half (15 MOA vs 7 MOA)? It's all based on the elevation change in MOA, and not necessarily the distance?

 

[Barrelnut]

That all sounds plausable, but I think you have an issue somewhere if the scope is setup correctly and you are 3/4 MOA right at 100 yards. Pic is of a tall target test I did at 100 yards dialed up 27 MOA. Notice how the top group really didn't change horizontal at all. They are 7 shot groups and I dialed up and down twice while shooting them. Not the best shooting on my part as the horizontal is me and coffee. But, the thing is this scope was leveled with a plumbob.

 

[xarcher]

The scope was set up with Wheeler bubble levels and never verified with the line test. So I guess the part I left out was the fact is that I was trying to verify whether the reticle was in line with the center of the bore. I confirmed that it was not perfectly aligned which I think is within the accuracy of the bubble levels.

But in the course of doing that, I came around to the belief that if I measure an offset at 15 MOA from a 100 yard zero, I would expect the same offset at 15 MOA from a 300 yard zero. Just was looking for validation of that is all.

By the way, keeping it on the line at 27 MOA is awesome.

Thanks

 

[ShtrRdy]

I think what you're saying is true.

Do you have a bubble level on the scope to check level for each shot? Assuming your tall target was aligned to a plumb line or long level.

 

[Biggs300]

When installing scopes on my last 3 or 4 rifles, I've used the Wheeler Professional Retical Leveling System. When used properly, this system takes the guesswork out of getting your scope's reticle perfectly level without troublesome cant. I have also use the system to install anti-cant bubble levels on my two long range hunting rifle and my benchrest rifle. It is a simple system and well worth the price in my opinion.

 

[tbrice23]

The scope was set up with Wheeler bubble levels and never verified with the line test. So I guess the part I left out was the fact is that I was trying to verify whether the reticle was in line with the center of the bore. I confirmed that it was not perfectly aligned which I think is within the accuracy of the bubble levels.

But in the course of doing that, I came around to the belief that if I measure an offset at 15 MOA from a 100 yard zero, I would expect the same offset at 15 MOA from a 300 yard zero. Just was looking for validation of that is all.

By the way, keeping it on the line at 27 MOA is awesome.

Thanks

One thing everyone should verify, check that the bubble reads the same one way as it does rotated 180° . Check this on a level flat surface. You would be surprised how many bubble levels aren't perfect.

Also, some scope's adjustments aren't precisely parallel to the crosshairs. So if you are going to dial your drops, calibrate your dial to the plumb bob line.
If a person wanted to hold on the crosshairs for his drops he would level his actual crosshairs to the plumb line.

Hope I'm making sense.

 

[MudRunner2005]

Years ago I bought a Badger Ordnance Dead Level...Never looked back. You level the scope in your rings on the Dead Level device, then put it on the rifle and finish the bore-sighting process.

https://www.midwayusa.com/product/1008828942/badger-ordnance-dead-level-reticle-leveling-tool-matte

 

[FearNoWind]

Commented in error .......

 

[Barrelnut]

Years ago I bought a Badger Ordnance Dead Level...Never looked back. You level the scope in your rings on the Dead Level device, then put it on the rifle and finish the bore-sighting process.

https://www.midwayusa.com/product/1008828942/badger-ordnance-dead-level-reticle-leveling-tool-matte

$145.00 Dollars? Bahahabahaa! LOL. A string and a fishing weigh ( or rusty cresent wrench ) are less than a buck! And proven to work! I'd be looking back. Looking back so I could kick myself in the arse.

 

[Bullet bumper]

I have a proper engineers level that I use on my lathe and other machinery so it also works ok on a rifle action . A string line plumb bob is a help but it does not tell you if the action is horizontal . You still have to get the action horizontal first and then plumb the cross hair in the mounts .

 

[el matador]

The only thing that matters when leveling your scope is that your scope level and vertical adjustments match up. The position of the rifle has such a minuscule effect that its not even worth considering. I like to level my reticle with the rifle for esthetic purposes but it does not significantly affect point of impact. I start out by lining up my reticle with a plumb bob and moving my scope level so the bubble is centered. The reticle does not always align perfectly with the vertical adjustments of the scope, so I use a tall target to make minor adjustments. If your gun is shooting off to one side with 15 MOA dialed in, rotate your scope level until your shots are in line. Problem solved.

I also think your drops are quite a bit off. You need 8 MOA to get from 100 yards to 300 yards? Sounds like you have the ballistics of a potato gun. With a 30-06 and a decent hunting bullet I would zero at 200 yards. From there you need only 10 MOA to get to your 550 yard mark, and you'll hit within 2" of your line of sight out to 235 yards.

 

[MudRunner2005]

$145.00 Dollars? Bahahabahaa! LOL. A string and a fishing weigh ( or rusty cresent wrench ) are less than a buck! And proven to work! I'd be looking back. Looking back so I could kick myself in the arse.

I'm sure in your life you've wasted more than $145 on something a lot less useful. I use the Dead Level all the time. For both mine and other people's scopes. Do I charge them? No, but that's because I'm not a douche to my friends. Has it paid for itself over the years, in my opinion, definitely. It's also easier to use because it takes the rifle leveling and movement out of the equation.