Advanced Marksmanship scope height to bore centerline

[dzander]

I've read /saw somewhere that old methods were to mount your scope as low to barrel as possible and today that's not necessarily so.
I was a a long range match yesterday and one of the top dogs was trying to help a young lady out after we shot the last stage. Looking at her gun fit/etc.
He mentioned that her scope could be a good bit lower to the barrel. Then he said why, his reason was the higher the scope the amount of cant is magnified.
I thought hmm , thats interesting, I never thought of that. We shoot out to 1000 yards there. thoughts?

 

[Diver160651]

The reasoning is wrong. Science wise ya, it is true, but way way low on the priority list.

The reasoning should be, gun fit. If the fit is not good, get a different height rings. There are many reasons some of us prefer not to have to tilt out head sideways to see through our scopes.. it overrides the tiny bit of difference a .25” ring height contributes to a cant issue

 

[Steel head]

I’d rather have my scope up a bit and the bore down a bit so recoil is squarely into my body and I can get a more comfortable position

Using cant and an excuse is idiotic my opinion.

 

[CoryT]

Another example of being technically correct but practically irrelevant. You probably cannot measure the difference it would make in a groups location, given the average amount of cant in position.

The gun needs to be setup in such a way that you can be completely relaxed in position, be able to fall asleep behind the scope and when you open your eyes you are all set to go.

Now, in an ideal world that's as low a mount as possible, we alter the stock to then fit the individual. Mostly this applies to a hunting rifle where snap shots from offhand are important. We have other issues though, like NVD compatibility, stock adjustment range and the fact that we most often shoot from some kind of supported position rather than an offhand snap shot.

If you try to shoot rifle trap like Jeff Cooper used to do in our 270 classes, a high mount will not work out well. That's not what we do in PR7, though on occasion we do see a mount that's so high we need to build up the cheekpiece to fit, simpler than changing rings.

 

[seansmd]

Great thread here with @Jack Master providing supporting data.

Rifle Scopes - Disadvantages to higher rings

Here is a great example Is this rifle crooked or straight ? Do we have to fix a cant? How about his one Now before I even address the rifle I can tighten the bipod and call it good, I put the cant in the Butt plate to satisfy my brain. I can feel it now, if this rifle is rolled the butt...

www.snipershide.com

 

[Jack Master]

Here is the post from that thread that shows the real effect.

I'll throw some calculus at this later to "Run the Math" rather than "Run the rifle"... outside is scary

View attachment 7317450



uhh...Ever run a ballistic program/calculator???..... yeah..... all math!! Go eat a bag of dicks.
Everything we do In long range precision shooting is Math... so, do the damn math.

 

[seansmd]

Thanks Jack, I linked the whole thread, it debunked a lot of the old knowledge dated information.