For Hair Bear ... optimal zero for your R 9..

[Yrrah]

Using your figures from below... MV 729 fps; ME 16.2 fpe; 13.73 gr Exact; 0.0273 BC; sight axis height above bore axis 1.50" ....

Here is a fair zero for you to hit a 1.5 inch kill zone ( ie +/- 0.75 inch of sight line ) from 5 yards to about 41 yards ....

Zero at 36 yards and you will also be zeroed at 11 yards. Make sure you have a very soft front rest when zeroing and no back rest ( if you are used to shooting without a rest in the paddocks etc. ). It is best to zero a spring rifle in the same way that you will shoot it in hunting as they are sensitive to the way they are rested or not rested.

Anyway you will see from this graph that you can do far better than zeroing for just one point of coincidence between your sight line and trajectory. Give it a go........ as to be within 3/4" of sight line over 5 to 41 yards is not to be sneezed at. ... Kind regards, Harry.
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[astro]

harry you are a valued resource mate, and very bloody helpful too....

how do you measure sight axis height above bore axis, is it the horizontal line of your sight and the imaginary horizontal line half way through the bore? if it is mine is 1.25" FPS 859 FPE is 14.6 Beeman FTS 8.9gr and no idea what the BC is or how to work it out

i would really appreciate the same information that you were able to provide to hair Bear

thanks in advance

carl

[Yrrah]

Give me some time and I'll see what I can do ...... Kind regards, Harry.

[Yrrah]

Reply sent to Hair Bear ... I'm not totally familiar with the way all this works with private messages etc., but am catching yp fast I hope:

All's fine here Andree.

If Lewis used the same pellet I would be sure the figures were correct when he did the test. I can't comment on what the status may be now but would think it should not be much different.

In respect of the ballistic charts... well the best in my opinion is Chairgun as the maths that underpin it are the best so far for diabolo pellets. I can personally vouch that if the input data is spot on quality data then the output will be excellent. I have tested it over and over again. Here is just one example:..

http://www.network54.com/Forum/79537/thread/1100002721/

Please enjoy the read, Kind regards, Harry.

[HAIR BEAR]

G'day Harry
yeah got your pm

[Yrrah]

harry you are a valued resource mate, and very bloody helpful too....

how do you measure sight axis height above bore axis, is it the horizontal line of your sight and the imaginary horizontal line half way through the bore? if it is mine is 1.25" FPS 859 FPE is 14.6 Beeman FTS 8.9gr and no idea what the BC is or how to work it out

i would really appreciate the same information that you were able to provide to hair Bear

thanks in advance

carl

Sight axis above bore axis:
Measure diameter of the sight bell and divide by 2 to get radius.
Measure barrel diameter directly under where you measured the sight bell and divide by 2 to get barrel radius.
Measure the gap between the sight bell and the barrel at the same point.

Add the two radii and the gap together and presto... you have the data!

You do that and come back with the result which will be somewhere in the 1.5 to 2.0 inch department and I will chase up a BC for your pellet ( I did one once but there are data bases that give a good idea ) and then we will get an optimum zero range for you.... Is a 1.5 inch kill zone OK or do you want smaller / larger? ............. Oh and are you near sea level or up in the sky? ....... Kind regards, Harry.

Edit PS ... I take it that is a .177 rifle not a .20 cal??? 0.20 cal FTS pellets weigh more than 8.9 gr.. about 11.2 gr ...... H

[HAIR BEAR]

G'day Harry
did my experiment out back , only could get 20 yards !!


well it is very close to the chart you made , will check tommrrow if i get a chance out to the 40 yard mark !!
done a 2 click to the right and this isthe result

THANK YOU HARRY
you have restored faith in my air rifle
Andree

[astro]

sorry harry...yes it is a .177 hw97k, tuned by lewis with a wtc 4- 12x 44 scope (it's green)

target size 1.5 inches is fine
i live 21 metres above sea level

the scope is actually lightly touching the rifle so the Sight axis above bore axis is only 35mm or 1.38 inches

thanks
carl

[HAIR BEAR]

G'day astro
how are you ?
how are you going with that hk97 of yours ?
mate i don't think the scope should be touching any where except on the mounts ! as close to the bore as possiable , but not touching !!!

[astro]

i am very well and the hw97k is great, a bit heavy but gee it is accurate, i will post some targets after a use harry's information

it is very lightly touching just the chequering around the objective bell (i think thats what it is called) i haven't had any issues with it. it holds it POI

cheers

[HAIR BEAR]

Good to hear all is well for you !
mate if its not causing problems , then its all good !

[plantboy]

HB, following Harry's advice, the results of your latest experimentation are much more closer to the performance I get from my .20 R9. I've found there is not a lot of difference between FTS and JSBs, with the latter having the edge in accuracy past 30m.

[Predator]

sorry harry...yes it is a .177 hw97k, tuned by lewis with a wtc 4- 12x 44 scope (it's green)

target size 1.5 inches is fine
i live 21 metres above sea level

the scope is actually lightly touching the rifle so the Sight axis above bore axis is only 35mm or 1.38 inches

thanks
carl

does your scope have mil dots?

[astro]

predator: no it does not have mildots

cheers

[Predator]

was gonna say, chairgun also has a scope view that shows where to align the mildots at various distances and at different wind speeds, its a pretty good little program!