To be blunt: No, nothing is wrong.
You now have real world data to correct your ballistics (aka: truing your calculator). True your calculator and move on....
BTW, might ask what weight bullet you're firing? 140gr?
Is scope alignment the issue?
- Thread starter cal_23
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You now have real world data to correct your ballistics (aka: truing your calculator). True your calculator and move on....
BTW, might ask what weight bullet you're firing? 140gr?
cal_23
Member
Thank you. Yep, 140gr eld-m. The required correction just threw me a little…..a right to left light wind with an initial windage of right 0.2 mils dialled, but I needed to dial left 0.5 to get onto the bull.
Thank you all for the comments and suggestions . All really useful to read.
So my 140gr eldm go a little quicker than yours 2780fps so would expect them to need a little less adjustment. At 900 mine use 7.6/7.7 mil so about 8mil for yours going slightly slower would seem reasonable.
All ballistics apps are ideal scenarios they are designed to get you there or there abouts. You will need to true it with real world data and some days the atmospherics are right and it all aligns some it’s not and you have to add a click or three. I use 2 different apps and take an average which works pretty well. (Hornady app, Applied Ballistics).
Also for windage Stickledown is an absolute F&£cker. You can be there look at all the flags make the correct call and it still wangs you out the side. If you ever get a chance for a Stickledown walk there do it, when you see the topography and things behind and along the danger area you see it’s never going to be a simple as the flags telling you the truth.
All ballistics apps are ideal scenarios they are designed to get you there or there abouts. You will need to true it with real world data and some days the atmospherics are right and it all aligns some it’s not and you have to add a click or three. I use 2 different apps and take an average which works pretty well. (Hornady app, Applied Ballistics).
Also for windage Stickledown is an absolute F&£cker. You can be there look at all the flags make the correct call and it still wangs you out the side. If you ever get a chance for a Stickledown walk there do it, when you see the topography and things behind and along the danger area you see it’s never going to be a simple as the flags telling you the truth.
This is why many who shoot Tikkas at long range in 6.5, tend to migrate to 130gr bullets; just to gain a little bit more velocity, without sacrificing a lot of BC. Tikkas are notorious for slow barrels in the 6.5mm caliber.
As above it could be so many things, could be not an exact true zero to start with, slightly wrong velocity, not true bc of bullet, tilted scope, calculator could be off, scope height ect there’s so many variables, realistically calculators are good to help you get on target but you need to learn your exact dope and write it down for future reference
I'm trying to get my head around this.
If the 'second cross-over' you're referring to is the zero (for the sake of argument, 100yds), then having changed to 20MoA mounts from standard mounts (of the same hight above the bore) and rezeroed at 100yds, I'd have thought the second cross-over will still be 100yds.
If you're on a firing-point and hitting at a thing at 100yds, the direction the rifle's pointing, and therefore its elevation, will be the same regardless of sight or mount - so the ballistic curve should be exactly the same regardless of the sight/mounts you're using - and I would therefore suggest that the 'come-ups' for various ranges ought to be the same, from a given zero-range.
Have I misunderstood something here?
Smellydog
Well-Known Member
The trajectory is not linear. It's radius decreases with time and distance.
With a 20moa mount inclining the scope down at the objective it allows adjustments to the scope closer to the center of adjustment range as opposed to working close to the end of the adjustment range when shooting at long distance.
This is done by raising the mid point height at normal distances.
With a 20moa rail you are lobbing the bullet higher and viewing it's return across the line of sight further away without having to move the reticle radically away from the center of the scope tube. In fact if you only ever shot a set up like above at short range like upto 200 yards one may possibly have to have the vertical turret quite a ways off centre!
When you see the distant bullet cross that line of sight the angle of incidence is slightly different to a parallel scoped angle of incidence.
That will change predictions made by computer programmes.
Still don't get it. The sight and mount will not affect the physics of the rifle with a particular load. Therefore, though the original setting of the sight will need to be changed when changing from standard to inclined rail, the settings between ranges, since they match the unchanged ballistics, really ought to be the same?
Do you think the Tikka factory made the bore of that barrel absolutely straight, and that the machinist timed it so that iif there was a high point, it was orientated to the vertical axis of the centreline of the rifle?
Also, BC’s are not true, you need to tune them based on data.
And, dont zero at 100, zero precisely at 200 or 300 and dial back to set your scopes 100 zero, that will reduce error at distance.
Also, BC’s are not true, you need to tune them based on data.
And, dont zero at 100, zero precisely at 200 or 300 and dial back to set your scopes 100 zero, that will reduce error at distance.
I don’t follow the logic here. Could you explain?
of course.
if you zero at 100m and have some small error, that error will magnify as you shoot further out. someone has already said have a very good zero, this is similar, but moving your "good zero" further out.
say your data says 12 clicks for 300m, shoot target at 300m and get a very precise impact at this range, and dial back the 12 click to set your 100m zero.
so whatever is happening at 100m is less significant than what is happening further out. but when you dial back out to your "good zero" and beyond, you will have less error.
of course the best thing to do is measure and record real dope at all given ranges, and not rely on a predictive curve generated by data which includes over ambitious BC's.
it works, try it
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Rusty Gate
Well-Known Member
130 RDF lasers!
Smellydog
Well-Known Member
Correct, the sighting does not effect the physics. Just where one observes the trajectory cross points to the line of sight.
The values are tiny, plus that with a slightly different velocity, plus a slight BC error, plus wind and it all accumulates error that then doesn't correspond to a computer program.
My advice would be Don’t stress it, you’re .3 mil out at half a mile on your first attempt. Everything is fine!
The discrepancy could be incorrect scope height or the fact the BC of the bullet doesn’t quite live up to what’s advertised.
The wind at stickledown can play silly buggers due to the tress etc. as above, note it down, see where you are next time.
That’s pretty much what I was going to say. 0.3 mil at that distance is ten inches or something. Could be anything. Don’t worry about it. You’re doing fine.
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