Bubble level??

[Bart B]

I bought one of these and I think they are great but for the life of me I can't figure why some one thought it is better to put the bolts in from the bottom. some times things needs comon sense too.

I'd guess the thing was made by a company that also makes scope rings for .22 rimfire rifles. All they had to do was use a standard top half for the bottom piece and make a new piece to hold the spirit level on top. A cheap but easy way to make one for low cost and high performance. But it might be a bit difficult to install on a mounted scope.

 

[MontanaRifleman]

I bought one of these and I think they are great but for the life of me I can't figure why some one thought it is better to put the bolts in from the bottom.
some times things needs comon sense too.

I didn't realize that. That sucks. What were they thinking?

 

[Dr. Vette]

Very interesting items - I can definitely see the benefit.

Now, a question - how do you "know" that you have them correctly levelled with your crosshairs? Use the plumb bob as mentioned earlier in the thread, and go from there?

The one that installs on the base looks interesting, but you have to "assume" that your base is inherently level. That seems a big assumption...?

Thanks for any additional input you may have.

 

[Southpaw]

Here's a couple more options:

Shawn Carlock's version (what I'm putting on my current LR build).

Defensive Edge Products


Four versions from US Optics.

http://www.usoptics.com/acc.php?typeID=Ext Cant Indicator


I have 3 ACD's from Sinclair International. Other than the Screws being on the wrong side, they work great.

Scope Levels



Southpaw

 

[MontanaRifleman]

I have the NF version of what Shawn offers and it's great. But it (both the NF and DE version) only fits NF rings and they are a little spendy @ $75.

The style that stick out sideways are not very usefull for hunting rigs that you carry.

 

[Bart B]

Now, a question - how do you "know" that you have them correctly levelled with your crosshairs? Use the plumb bob as mentioned earlier in the thread, and go from there?

I use the receiver flats where the bottom of the bolt's two lugs ride when it's opened. Others have used the sight base holes atop and on the side of receivers; put a very long shanked screw in one, then rest a small spirit level on it. to set the barreled action at the true horizontal or vertical.

It won't matter a whole lot if there's a small error. One can find out what the error is be comparing a 100 yard windage zero with a 1000 yard windage zero. Just shoot both ranges using the same position and zero wind conditions. If there's a small error, then your can correct it by slightly twisting the scope in its rings.

 

[MontanaRifleman]

I use the receiver flats where the bottom of the bolt's two lugs ride when it's opened. Others have used the sight base holes atop and on the side of receivers; put a very long shanked screw in one, then rest a small spirit level on it. to set the barreled action at the true horizontal or vertical.

It won't matter a whole lot if there's a small error. One can find out what the error is be comparing a 100 yard windage zero with a 1000 yard windage zero. Just shoot both ranges using the same position and zero wind conditions. If there's a small error, then your can correct it by slightly twisting the scope in its rings.

The only thing is that the windage difference @ 1000 yds maybe coriolis and/or spin drift and not cant.

I align my scope reticle with the plum bob method and also the anti-cant level. Then I shoot it at 100 yards going 20 MOA up and down using a 4' peice of cardboars or plywood with a straight, plumed line on it to confirm it. Once confirmed, I align the reticle and the plumb line @100 and readjust ny anti-cant if it needs it.

 

[Bart B]

The only thing is that the windage difference @ 1000 yds maybe coriolis and/or spin drift and not cant.

I doubt there's more than a 1/4th MOA error caused by coriolis and/or spin drift through 1000 yards. There's only 1/2 to 3/4 degree elevation angle above the horizontal for most cartridges to zero at 1000 yards. And the bullet's angle of fall at 1000 yards is just over 1 degree. Hardly enough to show the effects of coriolis and/or spin drift, in my opinion.

I've shot the same windage zero from 100 to 1000 yards with different 30 caliber cartridges and one 26 caliber one. I've got 100 yard zeros with new barrels then set the sights down equal to bullet drop plus sight height for mechanical elevation zero. Then made my usual come-ups for 1000 yards and windage (plus elevation) zero was good.

There's several internet sites showing that there really is a few inches of both horizontal and vertical deflection at 1000 yards caused by coriolis and/or spin drift. That's fine by me. In practical applications or even precise ones, the errors are insignificant. Us humans make more errors in judging windage corrections for cross winds than spinning bullets shot on spinning planets cause. I've shot long range in several places both above and below our planet's equator and haven't noticed any difference in windage zeros.