Chairgun

[Archer50]

For me, Chairgun has its uses, but it is not a substitute for real shooting.

I find it very useful for putting me in the right ballpark for a completely new set up and for checking out some ‘what ifs’ and comparisons, but I have rarely found a set-up where I could rely on Chairgun to give me accurate hold-overs straight off the screen.

Because I like fiddling with this sort of thing I have done some very careful checks using both direct measurement and the pinhole method for sight height, a Leica laser to measure the target distance (± 1mm) laboratory scales for the pellet weight, and a Combro shooting through a Skan for the MV. The results have been very variable. For my .177 HW100 shooting JSB Exact Heavy pellets, the results are pretty good – as good as I can shoot in real HFT/hunting situations. For my HFT 500 with JSB Exact 8.44’s the results are pants - around half a mil dot out at 45 yards and for my smooth twist Bobcat even worse. I don’t know enough about ballistics to know exactly what is going on, but since I can control just about everything else I assume that the problem lies, as others have said, with the BC. At least the results are better than Strelok which seems to be built around some sort of fantasy number generator!

[Mark112]

Hi,

Use the Chairgun software itself to calculate your own BC values. Use the 'Toolbox' ...' Calculate BC from ...' tools. There are videos on youtube but have a look it's fairly self explanatory. I use the facility to calculate BC from drop at range as its probably the easiest to do. Zero at 30 yards say and then shoot a group of shots at 50 yards. Use the drop at 50 dimension to input into Chairgun at it will calculate a BC to suit. It's still not perfect but Chairgun will tie up better with your own actual shooting figures.

Mark

[GPConway]

... it can't calculate for a tight choke or even the effect of a silencer.

True, but then it doesn't have to. Chairgun relates to external - not internal - ballistics and you measure the muzzle velocity at the muzzle not inside the bore.
A tight choke - or interference with the silencer - might affect the BC a little ... but you'd have checked that anyway, wouldn't you?

George

[Blackcat68]

si pittaway on you tube says to measure from middle of scope to middle of barrel,ive done it this way and it works bang on...

[GPConway]

Related - ish Q on Chair gun .. has folk ever struggled to get same results on PC vs Android version of chairgun ? Interestingly I get within X.X1 variation in PC vs Android versions of X-ACT

The current versions of Chairgun and X-ACT (desktop, Android and iOS) use a later algorithm whereas the Chairgun Android and iOS versions - which are now over 2 years old - use an older algorithm. This discrepancy, I’m told, will be rectified in the next Chairgun mobile release.

George

[gdavison]

Related - ish Q on Chair gun .. has folk ever struggled to get same results on PC vs Android version of chairgun ? Interestingly I get within X.X1 variation in PC vs Android versions of X-ACT

The current versions of Chairgun and X-ACT (desktop, Android and iOS) use a later algorithm whereas the Chairgun Android and iOS versions - which are now over 2 years old - use an older algorithm. This discrepancy, I’m told, will be rectified in the next Chairgun mobile release.

George

Cool TY