New user of chairgun.

[LESS THAN FORTUITOUS KENNETH]

How accurate is it? I'll narrow that down a bit. I put in all relevant data and set it to give me a thirty yards zero. Write down all the mil dot settings. If I then set it up in the back garden using the 10yd reading, should all the other readings then be fairly accurate? I'm not talking pellet on pellet, but accurate enough to be in the ball park when shooting say 40mm targets?

[lensman57]

How accurate is it? I'll narrow that down a bit. I put in all relevant data and set it to give me a thirty yards zero. Write down all the mil dot settings. If I then set it up in the back garden using the 10yd reading, should all the other readings then be fairly accurate? I'm not talking pellet on pellet, but accurate enough to be in the ball park when shooting say 40mm targets?

How accurate it is depends on how accurate the value of the BC is that is allocated to pellets. I find the values in the library a bit over optimistic for long range shooting. For example a JSB exact 8.44 has a qouted BC of 0.022 but I find that in my S400 this value is more like 0.019 . The good news is that if you restrict your shooting to 45 yards the error is small . You also need to give an accurate scope height otherwise all bets for short range precision are off. Once correct values are used the results are very close to reality.

A.G

[LESS THAN FORTUITOUS KENNETH]

Thanks for that. It should serve my needs then.

[poth]

You can't beat getting on the range with a tape pen and paper

[LESS THAN FORTUITOUS KENNETH]

I understand that. I did say "in the ball park". I shall only be using mil dots, not dialling in.

[Efferink]

I tried it for the first time this week at 25-40 yrds and used it as an initial aiming point guide in a 10 mph wind, and it was fairly close.
Hardest point was trying to find a reticle to match the Viper Connect.

But for a starting point I was pleased, checked the appp, aimed for the spot then fine tuned.

[DESERT FOX]

just use Hawke 10x half milldot as a guide for your viper.

[LESS THAN FORTUITOUS KENNETH]

Just been trying it on a tuned tx with 5-15 Hawke panorama. Gun running consistant 770ft/sec with JSB 8.44g. Scope mounted with centre 6cm above barrel. Mag set at 15x.
Got pellet on pellet at ten yds using the chairgun suggested aim point of +3.7 mil dots. Then went out to 20yds which should be 0.14 mil dots (which is only a gnat's off zero. Spot on! For about two shots, then suddenly dropped a couple of inches.
Reset the scope to hit 20 yds at zero. When I got several shots consistantly in the same hole, I brought the target forward to 10 yds and shot again at +3.7mil dots (as chairgun states). Pellet on pellet. So it seems chairgun works quite well.
The problem now is why did it do that sudden drop? Hope I haven't dropped on a scope that doesn't hold zero.

[lensman57]

Just been trying it on a tuned tx with 5-15 Hawke panorama. Gun running consistant 770ft/sec with JSB 8.44g. Scope mounted with centre 6cm above barrel. Mag set at 15x.
Got pellet on pellet at ten yds using the chairgun suggested aim point of +3.7 mil dots. Then went out to 20yds which should be 0.14 mil dots (which is only a gnat's off zero. Spot on! For about two shots, then suddenly dropped a couple of inches.
Reset the scope to hit 20 yds at zero. When I got several shots consistantly in the same hole, I brought the target forward to 10 yds and shot again at +3.7mil dots (as chairgun states). Pellet on pellet. So it seems chairgun works quite well.
The problem now is why did it do that sudden drop? Hope I haven't dropped on a scope that doesn't hold zero.

Bad pellet or inconsistent hold most likely.

A.G

[rhyslightnin]

How accurate it is depends on how accurate the value of the BC is that is allocated to pellets. I find the values in the library a bit over optimistic for long range shooting. For example a JSB exact 8.44 has a qouted BC of 0.022 but I find that in my S400 this value is more like 0.019 . The good news is that if you restrict your shooting to 45 yards the error is small . You also need to give an accurate scope height otherwise all bets for short range precision are off. Once correct values are used the results are very close to reality.

A.G

Our own Brian Samson said to me that the BC makes only a little different compared to scope height. Now he also told me that scope height isn't the center of the scope to the centre of the bore but the distance from the line of sight to the centre of the bore at the muzzle. You can figure this by setting the zero distance you want a then put a cover the objective of the scope with a small hole in the middle of it which will help it focus at the muzzle, then put a dot on a bit of paper aim at the dot with the muzzle as close to the paper as possible and fire. Then measure the distance from the dot to the pellet strike.
He also showed me a pic of the theory which I'm not sure where is now. After doing this with my huntsman I'm pretty sure it's 40mm accurate out to 75yrds (wind/power consistent and all the other factors considered).

[LESS THAN FORTUITOUS KENNETH]

I'm not quite sure I get that.

[LESS THAN FORTUITOUS KENNETH]

Bad pellet or inconsistent hold most likely.

A.G

I don't think so. It dropped and stayed dropped for quite a few pellets. I had to make quite a major adjustment to the scope to get it back on song. The scope was second hand (but like new), so it's always a worry that it might not be all it should. Lets hope it stays put now. I'll only be using mil dots and not dialling in.

[GPConway]

How accurate is it? I'll narrow that down a bit. I put in all relevant data and set it to give me a thirty yards zero. Write down all the mil dot settings. If I then set it up in the back garden using the 10yd reading, should all the other readings then be fairly accurate? I'm not talking pellet on pellet, but accurate enough to be in the ball park when shooting say 40mm targets?

Chairgun, like much ballistics software, will be as accurate as the data that you input.
If you make assumptions, then - depending on the magnitude of the errors - it can all go wrong pretty quickly.
Muzzle Velocity is easily the most crucial in all cases but, if shooting beyond the far zero is envisioned, Far Zero Range, Sight Height, BC and Environmental constraints become increasingly important depending on the target range.
Unless you're only ever shooting at close(ish) targets, always base everything on the Far Zero range rather than the Near Zero only because the NZR is so difficult to establish accurately and any errors will have a disproportionately large error on the FZR.

How accurate it is depends on how accurate the value of the BC is that is allocated to pellets. I find the values in the library a bit over optimistic for long range shooting. For example a JSB exact 8.44 has a qouted BC of 0.022 but I find that in my S400 this value is more like 0.019 . The good news is that if you restrict your shooting to 45 yards the error is small . You also need to give an accurate scope height otherwise all bets for short range precision are off. Once correct values are used the results are very close to reality.

A.G

The database BC value for the 0.177 JSB Exact is 0.021. If your Chairgun copy is giving the value as 0.022 then it's because you've altered it (either directly or indirectly by having the Configuration > Strategies: > Projectile DB Update Strategy ... setting set to something other than 'Never Update'). That said, the observed BC value can vary a little between pellet batches and barrels so you really need to calculate the value for yourself. Paying close attention and using two matched chronographs, I get (GA) values between 0.0196 and 0.0218 depending on batches.
The value for the 0.22 JSB Exact is much more consistent (GA again) at between 0.0309 and 0.0316.

Our own Brian Samson said to me that the BC makes only a little different compared to scope height. Now he also told me that scope height isn't the center of the scope to the centre of the bore but the distance from the line of sight to the centre of the bore at the muzzle. You can figure this by setting the zero distance you want a then put a cover the objective of the scope with a small hole in the middle of it which will help it focus at the muzzle, then put a dot on a bit of paper aim at the dot with the muzzle as close to the paper as possible and fire. Then measure the distance from the dot to the pellet strike.
He also showed me a pic of the theory which I'm not sure where is now. After doing this with my huntsman I'm pretty sure it's 40mm accurate out to 75yrds (wind/power consistent and all the other factors considered).

And Brian is right. Nice description of how to correctly measure the sight height too.

George

[rhyslightnin]

I'm not quite sure I get that.

Which bit?

[LESS THAN FORTUITOUS KENNETH]

Which bit?

"setting the zero distance" .... Do you mean on the focusing ring?

I get putting the hole in the lens cap to get close focus, But how close do you need to be to the target before firing at the marked dot?

I also envisage a problem when using a springer.

Not explaining it well am I?