Why height over bore does not matter
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One on top of two
Well-Known Member
Not watched vid .
But
The higher you are the centre of the bore , the easier it is to cant the rifle .
This is what I was always lead to believe.
How wrong am I ?
But
The higher you are the centre of the bore , the easier it is to cant the rifle .
This is what I was always lead to believe.
How wrong am I ?
StephenToast
Well-Known Member
Personally I find a lower mount is easier to get a consistent cheek weld.
Exactly this ^^^
Better cheek weld and better overall shooting position.
As long as I can slide a fag paper between my scope and my barrel I'm happy.
I agree that 'cheek weld' does give the wrong impression. But it is the cheek that should be on the butt, not the jaw. So, unless you have an adjustable cheek raiser, the lower the scope is mounted the easier it is to rest the correct part of the cheek on the butt. This allows a more comfortable and repeatable shooting position. A low mounted scope also alleviates the risk of canting by lowering the centre of gravity and helps to keep the reticle closer to its centre of travel.
nun_hunter
Well-Known Member
As long as you can get a consistent and comfortable position with your cheek/jaw then that's good.
Only issue with a high scope mount is when you have a close zero distance and then are required to take further away shots as now the the point blank range is either much less or you need a bigger target size to ensure hits without aiming off.
Only issue with a high scope mount is when you have a close zero distance and then are required to take further away shots as now the the point blank range is either much less or you need a bigger target size to ensure hits without aiming off.
Smellydog
Well-Known Member
As long as your head and eye are in the same place every time,( cheek weld) scope height is irrelevant , comfort is more important, if you are comfortable with your gun you will shoot it better. Only my experience, as for can,t it comes into effect at distance usually further than most people shoot deer.
Today, little Timmy would learn about 'scope bite'...
and a flinch.
Interestingly I would argue that the higher the scope is mounted the easier it is to avoid cant, you have a much larger indicator...
1˚ rotation around the barrel at 40mm height the horizontal linear offset between bore and scope is around 0.349mm. At 400mm 1˚ of rotation the offset is 3.49mm...much easier to detect.
At 5˚ of rotation as per @Sharpie 's description below the horizontal offset would be would be 1.745mm @40mm, and it would be 13.962mm @ 400mm.
But the clue to the OP is relating to accuracy not practicality..bit of a non question really. There is no reason you couldn't zero a scope set at any height...you would just be reducing your point blank range because you were "tangential" to a tighter curved section of the trajectory. Significantly less practical for short range...not much difference at long range.
Alan
1˚ rotation around the barrel at 40mm height the horizontal linear offset between bore and scope is around 0.349mm. At 400mm 1˚ of rotation the offset is 3.49mm...much easier to detect.
At 5˚ of rotation as per @Sharpie 's description below the horizontal offset would be would be 1.745mm @40mm, and it would be 13.962mm @ 400mm.
But the clue to the OP is relating to accuracy not practicality..bit of a non question really. There is no reason you couldn't zero a scope set at any height...you would just be reducing your point blank range because you were "tangential" to a tighter curved section of the trajectory. Significantly less practical for short range...not much difference at long range.
Alan
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Incorrect. The effects of cant are irrespective of 'scope height, or zero distance. Think of it this way, no matter what your 'scope height is, the bullet still drops exactly the same amount under gravity. Any cant moves the point of impact sideways, depending on the distance you are shooting to.
It doesn't matter what your zero distance is, or the height of your 'scope. the effect of canting will be the same., getting worse as the range increases.
Just as the optimum scope height is a function of the ballistics of your particular setup, the distances that you choose for primary and secondary zeros, and the amount of bullet rise in between.
I like to experiment using https://shooterscalculat
You can see the "raw" trajectory of the bullet by setting zero distance and sight height to zero. E.g. using the default values, in there, which are a 150gr bullet, muzzle velocity 2800 fps, ballistic coefficient 0.48. Not sure what chambering that that might be representative of, but we'll use those numbers an example.
At 100 yards the bullet has dropped by 2.32" from the muzzle. At 200 yards, 9.76"
You can then calculate the effect of say five degrees of cant. Which is drop x (cosine 5 degrees). The same calculation as for the "rifleman's rule" for when shooting up or down hill.
So at 100 yards five degrees of cant moves the POI sideways by 2.31"
At 200 yards the same 5 degrees of cant moves it sideways by 9.72"
This is very significant. Far more than normal wind effects. In this examplet would take approximately 30 mph of crosswind to have a similar effect to five degrees of cant. Which is easily done if e.g. shooting in a landscape which has few vertical or horizontal features to line up with.
if you are not consistent in holding your rifle to minimise cant. I'm sure that a lot of horizontal stringing seen on test targets that is attributed to variations in the wind is more likely just poor marksmanship/inconsistent rifle hold. Maybe even fit a bubble level to your 'scope to see how consistent you really are.
The biggest variable in the effects of cant is the velocity of your bullet. The faster/flatter shooting chamberings with high BC bullets are less susceptible.
You even see the episode of “Alaska the last frontier” Where the guys mrs did this with a 300wm?….epic fail!
Interestingly my mental picture of this comes from the other direction.
The vertical trajectory plane is the constant. Thus, when you cant the rifle you just move the line of sight to the side relative to the trajectory rather than shifting the point of impact....the line of sight is then going diagonally across the trajectory plane instead of parallel with it.
Alan
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