UM TIKKA Scope Rings

[solarshooter]

You are right.
SIN function will tell you the windage/elevation error caused by the corresponding elevation/windage holds/dials.
Increasing the cant angle increases the error trigonometrically
Increasing the hold/dial increases the error linearly

And yes, generally the elevation hold/dial is greater than the wind hold/dial, so its corresponding error is greater (error will be seen as a windage miss)


To measure the resolution of the bubble level graduations,

1. set the level on top of a straight edge of known length (like a 48" carpenter level for example. You are only using it as a straight edge though, don't worry about what the level's bubble shows. just watch the UM level.)
2. Shim the very outside edges of the straight edge until the UM level shows perfectly centered. This is now your starting point. Don't record the thickness of these shims.
3. Add shims (to either side, doesn't matter), until the UM's bubble is just touching the line. Record the thickness of ADDED shims.

Now the following calc will determine what angle it took to move the UM bubble to the line. Make sure your calculator is set to "degrees" if you want degrees:
TAN^-1(ADDED shim thickness / straight edge length)

A more precise way to do it would be to start with the bubble touching one line, then shim until it touches the other line. Do the same equation, and then divide by 2

Embarrassingly, it took me almost a year to finally do this check. Following your procedure using a 12" metal straightedge and different thickness allen wrenches as shims, here's what I got:
arctan(0.245/(11+14/16)) = 1.18deg

repeated with a slightly different method:
arctan(0.223/10) = 1.28deg

This is where the outside edge of the bubble just touches the line. So I'd call it ~1.2deg, within the precision of my ability to measure it.

So to answer my question from above:

For instance at 600yds, 1deg of cant produces sin(1deg)*3.5mils elevation = 0.06mils windage, so I probably wouldn't sweat being within 1deg.

Keep it inside the lines and you're good.

 

[Shortschaf]

Embarrassingly, it took me almost a year to finally do this check. Following your procedure using a 12" metal straightedge and different thickness allen wrenches as shims, here's what I got:
arctan(0.245/(11+14/16)) = 1.18deg

repeated with a slightly different method:
arctan(0.223/10) = 1.28deg

This is where the outside edge of the bubble just touches the line. So I'd call it ~1.2deg, within the precision of my ability to measure it.

So to answer my question from above:

Keep it inside the lines and you're good.

Thanks for the followup that is great information.

I'm the one who should be embarrassed. Thinking about this again, it should be arcsin and not arctan

I will edit my post, but I digress. This is a small angle approximation... arcsin ≈ arctan and your result will be the same!

 

[joshs]

Does anyone know if the low 34mm rings will fit with a Leupold 4.5-18x52 (or 6-24x52 since it's the same tube) on a Tikka factory lite contour?

 

[atmat]

Does anyone know if the low 34mm rings will fit with a Leupold 4.5-18x52 (or 6-24x52 since it's the same tube) on a Tikka factory lite contour?

 

[Dobermann]

View attachment 901996

Hey ... he's a new guy; cut him some slack.

@joshs - welcome. @atmat actually wants you here. He also just wants your scope to not lose zero.

 

[joshs]

Ha. I've actually lurked here a long time some I'm pretty familar with the drop evals. I have quite a few SWFA scopes and a Maven 1.2 as well. I do really like a lot about the new Mark 4 Leupolds, so hoping they won't lose zero when I look at them wrong.

 

[IrkedCitizen]

I dont know for sure but you will likely need mediums

 

[joshs]

34mm rings are still just high or low.

 

[IrkedCitizen]

34mm rings are still just high or low.

Buy both during the 4th sale and try the lows first. Return what doesn't fit

 

[plebe]

Threading and pounding in the recoil stops is such a pain in the ass with these rings.

And wish UM could make some lower rings too.