Holdover/under OR ?

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newbee

Member
Jun 19, 2021
49
4
Florida, United States
Hello to all !
Hopefully this is right section to ask. I have the fx wcmk3 with Optisan CP 3-12X32P (mil-MH10X.
I have only been able to shoot it a little due to working so dang much. It is sighted in and centered for 35 yards. What I've noticed is close shots like 10-20 yards I actually have to hold over ~4” (it shoots low from crosshairs)

It seems to be pretty centered 35 <>60 yards. Can / would someone explain this to me. I haven had the time to try longer than 60 yd shots yet. I been using jdb 15.89 pellets only so far.

Also which is best way to proceed, label scope with ranges an get a range finder?

OR

Get use to gun it is an learn the hold over an hold under!? 
Thanks


 
With the high scope over bore position of a bullpup more holdover at close ranges is expected. 4" sounds like a lot but I don't own a bullpup.

Do you know your scope over bore height? Speed of the 15.89 you're shooting? 

I would download the desktop version of Chairgun & play around with the parameters. It's a very basic ballistic program but it has been a great introduction for me.


 
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yes, its just the bore centerline in relation to optic centerline .. theyre different ... then youre dealing with an arc projectile trajectory ... the key is to 'zero' it to take maximim advantage of all factors to have the longest 'point blank' range within acceptable predetermined deviation .. a ballistics program helps you visualize all this .. but generally yes, theres holdover in both closein and far out ... when your dealing with extreme angle now like shooting uphill it adds yet another factor and In some cases you can even be holding under ...
 
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To give you the quickest visualization, where would your pellet hit in relation to the center of your scope if you held a piece of paper to the end of the barrel and fired? As much lower as your scope is mounted higher than your barrel on your gun.

You're shooting fast enough that at close range, basically, this is happening. So you have to hold over to raise the barrel up to zero.
 
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Thanks everyone! I will check out out chairgun an this video. I dont know speeds. Will add things a i go but next thing for me is a compressor. Crono and range finder later as I get confident with the gun. An yes shooting up high in a tree has been a challenge as well. No way to figure that one out. Hopefully this video an program will explain that. 
Thank you all fo your help. 
 
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Hello Newbee, I would advise against clicking just because in a hunting situation it's faster for me to use holdover, that being said my FX Royal 400 22cal is pushing JSB Hades 15.89gr at 935fps, my scope height is a lot less than yours mine is 2.06"

As others have said download ChairGun and play with it for me it's been spot on, check out the optimum zero range, for me if my first zero at 20.9y my second zero is 40y
What that gives me is at 16.5y I'm ¼" below the cross hairs, 20.9y I'm dead on, 33y is the apex of my trajectory of less ¼" above the cross hairs, 40y I'm dead on again and 44y ¼" below the cross hairs, long story short (to late) lol so anything from 16.5y to 44y I can put the cross hairs on it and it's ¼" above or below that equals a dead "target".

I'm using a 6.5~20 power SFP scope so on the outside of my front cap I've drawn the cross hairs and Mill Dots reference points at 20 power and on the eyepiece the same thing at 6.5 power.

To give you an idea here's a screenshot of ChairGun at 20 power. 

Screenshot_20210912-064526.1631454406.png

 
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It's a journey learning all the intricacies of this type of shooting using the holds with the reticle at different distances.

Inside 40Y one can have decent success ranging using the side wheel of the scope on 12x but most prefer to do it on higher magnification. So that makes using a rangefinder the easy button for the longer distances.

All your holds are based on a solid zero so always confirm you are sighted in first if possible because often airguns have poi shifts. Most use 30Y as their zero because that is at, or close to the top, of the trajectory for many airguns and scope heights shooting pellets in the 800 to 900 fps region. So that means all or 99% of your dope will be holdovers. I prefer it this way myself.

For close in shooting I'd do actual distances in 2 yard increments on small targets. I use a dot on the target that I draw with a Sharpy. You'll find there is a big difference in holds between 10Y and 11Y but the farther away you go out the difference in holds will be much less.

Using a ballistic program will get you really close but there's no substitute for actual confirmed drops and corresponding holds. Make sure you have the gun filled properly BTW or you'll have to do the work twice. You can figure out your dope well within 3-4 hours. A guy I know fashioned a target frame on wheels attached to a line so that he can set it out at whatever distance and drag it in for each distance he wants to check his holds verifying distance with his range finder.
 
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Yes, it’s amazing how the close shots can vary so much. I definitely feel better shooting 35 40 even 50 yards more so than 10 or 15 or 20. I’ve been shooting in 5 foot increment to figure out how much to hold over on the close shots. It a bit of walking.
That video from Ted’s holdover was very helpful on shooting up and or down. I would’ve probably shot my expensive drone LOL

I wonder how I ever hit a deer and dove back in the day I think my 30.06 was more forgiving than this wildcat We are getting it figured out though The journey is fun except the math needed to figure some of this stuff out.
Thanks everyone!




 
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