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Old 16th April 2015, 08:15 PM
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Conor Conor is offline
Never has been banned from sales
Join Date: May 2009
Member of: Nelson & Nomads airgun club
Location: Ardboe, Co.Tyrone.
Posts: 2,656

Originally Posted by Tench View Post
Brian I have measured the velocity of 8.44 Exacts at the muzzle and down range achieving a bc of .0267 over 27y in doors using my Hornet. I have also plotted the trajectory of my Gold Star by measuring from the cross hair. I drew crosses on a box and labelled then 8, 10, 12 etc to 45 yards. I put the box at the measured distance and fired 3 shots with the crosshair placed on the cross, I did this at each distance (measured) and arrived at the following measurements for the poi from the cross hair. The scope height is 1.6" JSB exact 8.44gn @ 784 fps.
8y -11mm
10y -5mm
12y 0
13y +2mm
15y +7mm
20y +15mm
25y +21mm
30y +23mm
35y +21mm
40y +7mm
45y -5mm
Now plotting this in CG and juggling settings to make it fit requires a bc in the region of that measured with my Hornet and it still doesn't quite line up with the actual achieved poi's but this is the trajectory the rifle is shooting. It would also seem the actual optical line of sight is slightly above the measured scope centre as using 1.7" aligns the poi's better.
Doing it this way eliminated scope magnification and reticle spacing errors.
27yrds is too short, the proper acid test is 50yrds as it is the longer distance that will really expose good dow range energy retention. BTW with a MV of 784fps, you would need to be seeing 635fps or more which is equivalent to BC 0.027, my Steyr is 0.0265 with good pellets and it will drift a pellet by 60mm at 55yrds in a 5mph side wind
He who never made a mistake never learned!
He who never missed never shot!

Last edited by Conor; 16th April 2015 at 08:21 PM.
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