Scope height

[Essarem]

not sure if this will help. https://airgunaccuracy.wordpress.com...-scope-height/

Thank you - I'll work my way through that!

[Essarem]

Without trying to be a smart arse I really despair at some of the rubbish that is written about how the trajectory of a pellet should be calculated.
First of all the Max shooting distance in HFT is only 45 yards. At 45 yards an air gun firing a typical 8.44 grs pellet ( most probably JSB exacts ) @ 11.5 ft.lbs will only have a drop of 2" if the gun is zeroed @ 25 yards and 1.7" if the gun is zeroed @ 30 yards. What this means is that if a killzone of 15mm is specified, from 16 yards to 31 yards no real correction needs to be given.
A typical scope @ 8X ( the most common mag setting for HFT ) will cover from 17 yards to 47 yards within one mildot of the reticule, the 0.5 mildot will correspond to 38 yards with the exception of very close ranges , where 8 yards will require 2 mildots and 10 yards only one mildot of correction . The scope height for these calculations was set at 4.5 cm which is the most comfortable height for a 44 mm objective scope for an average guy but everyone is different so a little experiment is needed to match the scope to the gun and the shooter. Increasing the height to 50mm will really only affect the close ranges adding an extra half mildot to the above values but as a rule I wouldn't recommend too high a scope height as it will make prone shooting ( most of the shots are taken in prone position ) rather uncomfortable.
Hope you will find this useful.

A.G

Yes, that is useful - thank you

[ChrisC]

i thought he meant the writer of the scope height article

I did mate

edit... does anyone know if Andy is James Maclachlans Dad? or is the author another Andy Mac?

[lensman57]

Yes, that is useful - thank you

You can actually download the free software Chirgun Pro from Hawke's site and play around with the parameters. Up to 50 Yards the given values are quite close to what happens in reality. For JSB 8.44 use a BC value of 0.02 and 0.018 for the JSB express and 1/2 Mildot for the reticule setting.

A.G

[Rotherham Owl]

I suggest you experiment - a lot!

Chairgun can be useful to look at the effects of different combinations of scope height/velocity/magnification on the trajectory and your aim points. When you find a combination that you think may work for you, check it out with your kit to see if it is accurate.

I started out using a 30 yard zero and now use one a bit over 40 as it suits me and my set up.

Once you find a zero you like, give yourself a decent amount of time to get used to it.

[Essarem]

Many thanks for all the advice folks - much appreciated.

All I have to do now is put the work in!

[bighit]

You can actually download the free software Chirgun Pro from Hawke's site and play around with the parameters. Up to 50 Yards the given values are quite close to what happens in reality. For JSB 8.44 use a BC value of 0.02 and 0.018 for the JSB express and 1/2 Mildot for the reticule setting.

A.G

i believe this was written due to people not getting the right results via chairgun and that was the reason i posted in on this thread and i'm sure people had said it had helped them get the right accurate results via chairgun.

it was on here more than once .

https://airgunaccuracy.wordpress.com...-scope-height/

[Muskett]

I suggest you experiment - a lot!

Chairgun can be useful to look at the effects of different combinations of scope height/velocity/magnification on the trajectory and your aim points. When you find a combination that you think may work for you, check it out with your kit to see if it is accurate.

I started out using a 30 yard zero and now use one a bit over 40 as it suits me and my set up.

Once you find a zero you like, give yourself a decent amount of time to get used to it.

^ This.
Cheek weld comfy, then worry about the rest. The pure exercise of sorting it out goes a long way to understanding your rifle combination. Its shooting, its fun, it does your head in at times. Once sorted then practice a lot, and in different conditions. A zero is just the start line, but getting a "full" zero to all practical ranges is not just a few shots off the bonnet of the truck.
Those familiar with their rifle having invested time and resources getting to know them are the ones that can pull off the tricky shots. Everyone else, myself included, just make excuses....and we know a lot of excuses

Lastly, once the zero is found, leave it alone. Rifles rarely lose zero, but they get changed far too much chasing other errors and the conditions. A .22LR of mine hasn't had its zero changed for 15 years, same ammo. I won't alter zero unless proven on more than two occasions, for too often I've clicked three to only have to click three back a few days later.

[krisko]

I'm new to airgun shooting and trying my hand at HFT. I saw in a recent article in Airgun Shooter that "for scope reference points to correspond with the trajectory of an 8.4 grain, .177pellet flying at 785 fps it is necessary to mount the scope 2.2 inches (57mm) above the BCL to maximise pellet trajectory with set aiming points visible in the reticle"

Assuming BCL is barrel centre line (?) my MTC Connect is set 2.0 inches above it on my AA S400. Is the 0.2 inches difference important do you think? If so how do I get the extra distance - put shims in the mounts? Grateful for any help.

2.2 inches is very high, you will have trouble initially at close shots. massive holdover.