Scope height & wobble zone?

[Hoyt7mm]

I had something interesting happen over the weekend when I took 2 rifle out to burn through some leftover ammo. Both rifle are identical to each other, except that one has a 1.5" Sphur, and the other has a 1.25" ARC rings. When doing barricade work, the rifle with the lower rings had consistently smaller wobble zone and I felt more connected. Not talking much, but enough to notice, and enough to be shown on target. I messed around with buttstock adjustments on the other rifle to try and get it feel the same, but couldn't make it happen. Has anyone else noticed something similar?

 

[KnowNothing256]

When you said buttstock adjustments, do you mean cheekpiece height? Or something else? The only other difference that jumps out is that the Spuhr mount likely adds some weight to the rig.

 

[Hoyt7mm]

When you said buttstock adjustments, do you mean cheekpiece height? Or something else? The only other difference that jumps out is that the Spuhr mount likely adds some weight to the rig.

I played with buttplate height and cheekpiece. When setting both up, I took balance into account and made sure both balance at the same location. I also tried and strings with and without bipods attached. Results were the same.

 

[Dthomas3523]

If it’s actually noticeable and repeatable, then one setup works better for you. Which makes sense. Different people have different bodies, likes, dislikes.

In your case, it may be the scope height.

But, that’s not going to be a set rule of thumb. As in, everyone won’t have less wobble with lower mounts across the board.

 

[Gregor.Samsa]

That scenario actually makes sense considering the higher mounted scope is further from the axis of motion. Every movement of the rifle will translate to more motion in the scope.

 

[KnowNothing256]

That scenario actually makes sense considering the higher mounted scope is further from the axis of motion. Every movement of the rifle will translate to more motion in the scope.

Well, motion around one of three axes would get magnified, the axis that is parallel to the bore. The axes that correspond to up/down and left/right on the target would be essentially unaffected.

 

[Holliday]

Well, motion around one of three axes would get magnified, the axis that is parallel to the bore. The axes that correspond to up/down and left/right on the target would be essentially unaffected.

I see new shooters holding their scope while shooting at a bench, then complaining about their groups. I suggest they don’t do that because it acts like a lever.

 

[KnowNothing256]

I see new shooters holding their scope while shooting at a bench, then complaining about their groups. I suggest they don’t do that because it acts like a lever.

Agreed, for tiny groups off a solid rest it's a bad idea. However, gripping the scope is a highly popular method of reducing wobble off of barricades in PRS-style competition.

I'm honestly surprised at OP's problem, unless it's a side-to-side wobble induced by minute rotations of the rifle around the bore axis. OP, were you seeing an increase in side-to-side wobble specifically, or the entire "figure 8" wobble was larger?

 

[flyright]

A lazy hand over the scope probably hurts nothing. However, I've seen shooters using the scope as a handle to carry the rifle and, also, press hard on the scope to jam the rifle into an odd barricade or other rest. Now, I'm sure that Spuhr's and others look and feel as though one could rappel with them but, I'm pretty sure that's not a good idea. And, I've seen plenty of f'd up shots from those shooters doing it to support my belief. The height above bore might contribute to wobble since it makes a longer lever but seems more like sorting pepper grains to me. Just my .03.

 

[Gregor.Samsa]

Well, motion around one of three axes would get magnified, the axis that is parallel to the bore. The axes that correspond to up/down and left/right on the target would be essentially unaffected.

You articulated this much better!

 

[Seymour Fish]

Longer lever arm. Think “axial”