Chairgun

[Sake-san]

I know Gary, just find it a shame that so many are armchair shooters!, having said that the future shall bring, without doubt, increased control & legislation so perhaps some may find their solace in virtual shooting

[gary martin]

It will not quite be the same, virtual verses actual.

[rhogg4696]

I just did the measuring as per the tinfoil method on two guns and the result was 1mm less and 2mm less than the normal method for measuring the scope height. Which was as predicted by the trig expert.

[Mark112]

Hi,

I've just had a play with Chairgun and changed my 'End Range' figure to 10 and changed the table to show every 1 yard. My scope height is input as 1.96" and at 1 yard the figure reads -1.78". As my barrel is say half a yard(ish) this would give say =1.87" at this distance. This figure is 90 thou or about 2mm in new currency. To me this means that Chairgun has got it pretty much right assuming that the scope height distance is measured at the turrets NOT the end of the barrel.

On a separate note to the Chairgun doubters out there Yes there is no substitute for range time but I have found that inputting my own data as accurately as I can including BC values gives me pretty accurate results and allows me to use the software to do a lot of analysis that I cannot do due to the dreaded work stuff etc. It's a useful tool to myself and many others. My last set of range tests out to 50 yards matched Chairgun's predictions within a couple of mm so pretty close I hope you agree.

Mark

[gary martin]

Hi,

I've just had a play with Chairgun and changed my 'End Range' figure to 10 and changed the table to show every 1 yard. My scope height is input as 1.96" and at 1 yard the figure reads -1.78". As my barrel is say half a yard(ish) this would give say =1.87" at this distance. This figure is 90 thou or about 2mm in new currency. To me this means that Chairgun has got it pretty much right assuming that the scope height distance is measured at the turrets NOT the end of the barrel.

On a separate note to the Chairgun doubters out there Yes there is no substitute for range time but I have found that inputting my own data as accurately as I can including BC values gives me pretty accurate results and allows me to use the software to do a lot of analysis that I cannot do due to the dreaded work stuff etc. It's a useful tool to myself and many others. My last set of range tests out to 50 yards matched Chairgun's predictions within a couple of mm so pretty close I hope you agree.

Mark

the scope height is technically measured from center of bore to the line of sight directly above the muzzle.
agree that it is a useful tool and puts you in the ball park, some fine tuning of the results may be required.
Gary.

[Sake-san]

On a separate note to the Chairgun doubters out there Yes there is no substitute for range time but I have found that inputting my own data as accurately as I can including BC values gives me pretty accurate results and allows me to use the software to do a lot of analysis that I cannot do due to the dreaded work stuff etc.

Don't worry, I play with it and other software too from time to time but, would never, ever rely upon it for final calibration. I am fortunate to have a 100m range in the paddock, which precludes the need for regular club / range visits.

[Mark112]

the scope height is technically measured from center of bore to the line of sight directly above the muzzle.
agree that it is a useful tool and puts you in the ball park, some fine tuning of the results may be required.
Gary.

The reason I suggest it may be measured from the turret it that you cannot accurately measure it at the muzzle. One reason is that it is physically awkward to do and the second is that the muzzle to scope centreline changes with your zeroed range so is not a fixed value (a 5 zero will angle barrel up more
than a 30 yard zero). I have read the help files from Chairgun and they do not mention at what specific point this dimension is obtained, muzzle, turret or otherwise (at least not in my help files). I have however sent an e-mail to the Chairgun people asking the question though and hope for an answer at some point.

Mark

P.S Sake-san. You are a lucky man with 100m to play with.

[gary martin]

You can not accurately measure from the turret. When you alter the click value the tube inside moves. I have explained how to measure the scope height in a previous post, it could be done via trig it is at the muzzle end. This is where acceleration due to gravitational force impacts on the pellet.

[Brooksy]

Chairgun gave me a pretty good idea of ranges but to be honest, as said before, it can't calculate for a tight choke or even the effect of a silencer.

There's no substitute for range testing.

[Bosun]

Another appraoch is ordinary trigonometry. Example: suppose you can actually measure accurately the axis of the scope (sight line) with the axis of the barrel. (Even with a breakbarrel and some barrel droop these assumptions hold.) And assume the drop of the pellet to the first zero point is neglegible. The distance from the scope-objective to the muzzle is relatively small compared to the distance from de muzzle to the first zero point.
Example:
Distance scope-axis to barrel-axis at the scope: 3.9 cm
Distance scope objective to muzzle: 50 cm
Distance scope objective to first zero point: 1500 cm
Then the corrected scope height at the muzzle would be: 3.9 x (1450/1500) = 3.77 cm (so just over 1 mm difference)

I am not sure how you come about the "Distance scope objective to first zero point". For example I am zeroed at 50m so my first zero is around 12m and not anything like 1.5m.

1500cm is 15m, which sounds about right to me for a secondary zero point.

I've tried both methods (pin hole & above) and got 46.1mm & 46.9mm respectively (scope to breech = 47.85mm), so a mill or so difference as suggested. But it still doesn't make ChairGun correlate very well with my "real world" data. I'm off to re-check my real world data just to be sure.

On the subject of ChairGun Pro, how do you find the latest version(V4.2.6.)? Personally, I prefer the former version (ChairGun3 1.0.5a), it's more intuitive and displays a more sensible/useful reticle image. Or is it just me can't drive the latest version?