Scope height

[Essarem]

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.

[bighit]

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

[angrybear]

Don't worry about it, with a different velocity you'll get a different trajectory.
You need to find the most consistently accurate (ie best grouping) pellet for your combo & then shoot it at every 5yds noting from the poa to poi how much hold-over your set-up requires at the specific range, you would need to do that anyway to confirm any theoretical results.

[ChrisC]

Hmmm, although that might seem like a starting point i would almost guarantee that most HFT shooters have varying scope heights and that's assuming a true mil dot ret. I use a 10x42 sightron on a Steyr LG100 and have no idea how high the sightline is from the BCL. I have medium/high mounts fitted and a 37 yard zero that makes my aim points fall into 1/4 mil dot brackets at the most frequently shot ranges. Some shooters choose a 25 yard zero as then they only need to use hold over, it's good for the closer small kills but gives large gaps on the longer targets.

45 yards = 1/2 mildot
40 yards = 1/4 mildot
37 crosshair
35 as near as dammit..crosshair
30 yards = 1/4 mildot
25 yards = 1/2 mildot
20 yards = 1/4 mildot
15 yards = crosshair
13 yards = 1/2 mildot
10 yards = 1 mildot
8 yards = 1.5 mildot

I reckon that if you took the top 50 HFT shooters in the country they would mostly have different rifles, scopes, mounts, scope heights, different sightline/BCL, different pellets, different zero's....et al.

In other words, try and get to a club with some decent HFT shooters and pick their brains and then after many years of trial and error you'll find what suits your eyes/shooting style/shooting position.

BTW...who wrote the article?

[bighit]

Hmmm, although that might seem like a starting point i would almost guarantee that most HFT shooters have varying scope heights and that's assuming a true mil dot ret. I use a 10x42 sightron on a Steyr LG100 and have no idea how high the sightline is from the BCL. I have medium/high mounts fitted and a 37 yard zero that makes my aim points fall into 1/4 mil dot brackets at the most frequently shot ranges. Some shooters choose a 25 yard zero as then they only need to use hold over, it's good for the closer small kills but gives large gaps on the longer targets.

45 yards = 1/2 mildot
40 yards = 1/4 mildot
37 crosshair
35 as near as dammit..crosshair
30 yards = 1/4 mildot
25 yards = 1/2 mildot
20 yards = 1/4 mildot
15 yards = crosshair
13 yards = 1/2 mildot
10 yards = 1 mildot
8 yards = 1.5 mildot

I reckon that if you took the top 50 HFT shooters in the country they would mostly have different rifles, scopes, mounts, scope heights, different sightline/BCL, different pellets, different zero's....et al.

In other words, try and get to a club with some decent HFT shooters and pick their brains and then after many years of trial and error you'll find what suits your eyes/shooting style/shooting position.

BTW...who wrote the article?

this guy possibly ?

http://www.anstonftc.co.uk/tag/hft-tips/

[Essarem]

Hmmm, although that might seem like a starting point i would almost guarantee that most HFT shooters have varying scope heights and that's assuming a true mil dot ret. I use a 10x42 sightron on a Steyr LG100 and have no idea how high the sightline is from the BCL. I have medium/high mounts fitted and a 37 yard zero that makes my aim points fall into 1/4 mil dot brackets at the most frequently shot ranges. Some shooters choose a 25 yard zero as then they only need to use hold over, it's good for the closer small kills but gives large gaps on the longer targets.

45 yards = 1/2 mildot
40 yards = 1/4 mildot
37 crosshair
35 as near as dammit..crosshair
30 yards = 1/4 mildot
25 yards = 1/2 mildot
20 yards = 1/4 mildot
15 yards = crosshair
13 yards = 1/2 mildot
10 yards = 1 mildot
8 yards = 1.5 mildot

I reckon that if you took the top 50 HFT shooters in the country they would mostly have different rifles, scopes, mounts, scope heights, different sightline/BCL, different pellets, different zero's....et al.

In other words, try and get to a club with some decent HFT shooters and pick their brains and then after many years of trial and error you'll find what suits your eyes/shooting style/shooting position.

BTW...who wrote the article?

It was Andy McClachlan - page 54 of the latest issue

[Essarem]

Thanks for all the advice folks - much appreciated!

[bighit]

It was Andy McClachlan - page 54 of the latest issue

i thought he meant the writer of the scope height article

[lensman57]

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.

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

[Essarem]

i thought he meant the writer of the scope height article

That's what I thought he meant and the writer of the article was Andy McClachlan

[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

Thanks - that is indeed useful

[cooper_dan]

When you look at other peoples setups, remember that the good shooters will have learnt how to set their scopes/guns up to help them most where they need it.
For example I know people who have high scope mounts because they struggle to range the furthest targets. (High mounts flatten out the trajectory at long range, and make it loopier at close range).
Other people use very small objective scopes and low mounts to flatten out the shorter ranges.

Of course sometimes the small objective scopes are used to get less parallax error, or that just happens to be a brand they liked, or they don't have an adjustable stock and need a low scope to get proper eye alignment.

I use a scope/mount combo that makes prone shooting comfortable with my non-adjustable stock. Just happens to be 4.5cm ish.
Pellet speed or magnification can be adjusted to get your aim points where you want them

[Essarem]

When you look at other peoples setups, remember that the good shooters will have learnt how to set their scopes/guns up to help them most where they need it.
For example I know people who have high scope mounts because they struggle to range the furthest targets. (High mounts flatten out the trajectory at long range, and make it loopier at close range).
Other people use very small objective scopes and low mounts to flatten out the shorter ranges.

Of course sometimes the small objective scopes are used to get less parallax error, or that just happens to be a brand they liked, or they don't have an adjustable stock and need a low scope to get proper eye alignment.

I use a scope/mount combo that makes prone shooting comfortable with my non-adjustable stock. Just happens to be 4.5cm ish.
Pellet speed or magnification can be adjusted to get your aim points where you want them

Thanks for the advice - I appreciate you taking the time. I have a lot to digest!

[cooper_dan]

With HFT you will find that almost everyone wants to help and has all the time in the world for new shooters. I've only been shooting a year and learnt so much by going to clubs and talking to people.

Back to the scope height question, have a look at the second to last graph on my latest blog. That is a slightly exaggerated example of how scope height can affect trajectory. But honestly I wouldn't worry too much about it until you have done a few shoots and have worked out where your shooting is strongest/weakest. Then tailor your setup to suit

LINK HERE

[dayglowfroggy]

Not that I am an expert but I think your scope height should go on what is CX the most comfortable with that stock and your face not on what people tell you or a graph says.
When I started hft people kept saying you want the scope really low so I did this but have since found my face shape suits higher mounts in fact high mounts on my tx gives me much better results , means I can have a comfortable head c up position instead of squishing my face into position.