chairgun help please
After getting .25 standard edgun back from Ernest its doing a lot better . But the chairgun program,is not quite right it was almost 1 mill dot off at 115 yards . the gun is shooting high , had to change BC to.460 my setting are jsb 25.40 bc .0460 910 ft/s 2.24 in scope height far zero 54 yards incline 0 wind 0 wind ang 90 61 temp 29.12 pressure 4.1880 c/moa 643 altit 40 humid target 115 yd scope is 6-24-56 hawke . at 115 yards it shows i should shoot middle of top block but pellet is hitting high almost first mill dot above block so i changed BC to .0460 from .0360 I have not shoot at other yardage so i don’t know if it will be right need some help please thanks
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Chairgun is perfectly accurate when you input the correct info.
Chrony your pellet at muzzle and at 100 to get your BC.
Mine is spot on out to 200 on both my Eds and scopes.
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Mine was off too, then I found my reticle setup was wrong on the app. :suprisedn: Now they both match. I’ve only been using chairgun for the click values from 20 to 90 yards. So far it’s been really close for me.
My phone app and computer app each give different results too.
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I found chairgun to be off. Today at the range it said sight in at 22yards and at 46yards it would be back on the crosshairs. I laser ranged 22yrd sighted it then moved to 46 and we were shooting a mil-dot high on my hawk panorama 1/2mil reticle. I was shooting JSB king at avg of 970fps. So my BC isn’t the same because I measured the scope hight carefully.
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I retried the chairgun app yesterday and it was off by .2 mils at 110 yards. Previously when I tried it over a year ago it was off by much more.
same here. works for me too
I need to use my chair gun app!
Works well for me too….
Exactly. I found Chairgun pretty accurate out to 100 yards for airguns if I use my own avg calculated BC. That is how I shot my first chrono. :suprisedn:
Chairgun is made for pellets. it works perfect for me from 10 to 50 yards. It has a calculator for BC. You measure the velocity at the muzzle and again down range at a known yardage so you get the exact BC of your chosen pellet in your actual barrel. The clicks on my elevation tape are dead on. Mil dots will change with magnification on most scopes.
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the problem with ballistic programs comes from the fact that most people don’t input the proper numbers. They use numbers that are given as averages and at 150 plus yards for an airgun or 1K yards for a 6mm VLD bullet averages just don’t cut it. To be accurate we need to employ miller’s formula and figure out drag and BC in real world applications. By experimenting and accumulating real world data one can learn the projectile better and the rifleman can choose optimum velocity that will maximize his rifle. Sure one does’t have to do that and marking down drops works too but I enjoy the obsessive nature of being precision rifleman.
here’s a calculator that can help if you want to obsess over long range shooting.
http://www.jbmballistics.com/cgi-bin/jbmbcv-5.1.cgi
My biggest issue with ballistic apps is they’re not really setup for pellets wind drifts, which are totally different then rimfire or center fire rounds.
The real problem with BC is that existing BC’s are all modeled on supersonic projectiles. BC does not actually change with velocity _if_ you remain supersonic. BC is a function of bullet weight and a coefficient that describes the drag of the bullet as it penetrates the air. The problem is that in the transonic region (velocities around 1000fps) the drag changes dramatically, it is then further reduced when you are fully subsonic (sub-900ish, depending on conditions). At subsonic velocities drag is significantly diminished from supersonic velocities, which is why your pellets are striking higher than modeled. There are numerous ‘drag curves’, but they were all developed with supersonic projectiles, so they model subsonic performance poorly. If anyone has created a subsonic drag curve, I’m unaware of it. Most software tries to model subsonic behavior (if it even accounts for it) by using piece-wise segments of supersonic curves.
GsT
I also had the same results when I tried to use chairgun, and found it to be very inaccurate. I tried messing with the BC like you did, but then it throws all of your other numbers off at other distances. I purchased a couple of different iPhone ballistic calculator apps and they are accurate. My favorite app so far is Ballistic AE. Using JSB 25.4, 0.036 BC, click the weather button to download the local weather conditions, and it is very accurate.
Lead,
the problem with ballistic programs comes from the fact that most people don’t input the proper numbers. They use numbers that are given as averages and at 150 plus yards for an airgun or 1K yards for a 6mm VLD bullet averages just don’t cut it. To be accurate we need to employ miller’s formula and figure out drag and BC in real world applications. By experimenting and accumulating real world data one can learn the projectile better and the rifleman can choose optimum velocity that will maximize his rifle. Sure one does’t have to do that and marking down drops works too but I enjoy the obsessive nature of being precision rifleman.
here’s a calculator that can help if you want to obsess over long range shooting.
http://www.jbmballistics.com/cgi-bin/jbmbcv-5.1.cgi
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So Chairgun is a bit off for me on my new set up. It is very close on my Challenger at 800fps with the 8-32 Leapers scope at 1.8 inch height. But it is 8, 1/4 moa clicks off between 12 yards and 26 with my TalonSS .177 at 840fps with the Leapers 4-16 at 3.4 inches high. I think the way to tweak the program will be to cheat the value for the scope height to get the 12 to 26 yard ranges correct. And then cheat the BC to get the 40 to 60 yard ranges dialed in.