Holdover or Holdunder

[CampFussell]

Tom Gaylord explains in pretty good detail what I was attempting to explain in my first post.

He even mentions the rise of the pellet between first and secondary zero isn't much more than a pellet width. Which is why I try to adjust my zero to graze the top arc of the trajectory.

https://www.pyramydair.com/blog/2005/06/at-what-range-should-you-zero-your-scope/

 

[DeadEyeNC]

Here is my explanation of holdover using one zero. Some use two zeros with both holdover and holdunder, but that can be confusing for some as well. This explanation is meant to keep it as simple as possible.

https://youtu.be/6rary5zbitk

 

[CampFussell]

Yay, Deadeye saves the day! Well explained Mr. Hepler ;-)

 

[BigTinBoat]

No airgun that I'm aware of could possibly have a close zero at 25 yards unless the scope has differently elevated ring mounts or an outrageous stack of shims, so anything over 25 is going to require some degree of holdOVER.

If his gun is what I mentioned (Mrod .22 shooting 18.1jsb at 850fps with his scope 2" above the bore zero at 25yds) then his close zero would be 25yds and his far zero would be 29.5yds.

The pellet would "peak" at 28yds.

Try these #'s in any of the ballistics programs.

 

[nced]

Easy way to tell.....shoot a target at different distance. Here is a target I shot with my .177 R9 zero'd at 30 yards using 7.9 grain CPLs........



Kinda easy to see that on at every distance from 15 to 35 yards and over for all other distances ON THE LEVEL. Add steep angled shots into the mix and it's a whole new game where the aim needs to be held low. When practicing steep angled shots I've had situations where I centered high pinecones at 40 yards by aiming "dead on" using a 30 yard zero.

Anywhoo....simply take a piece of paper, mark several rows of squares, then shoot each row at different distances, you'll have your trajectory chart.

 

[fishinwrench]

If you are shooting at typical velocities (about 850-900 fps), using your provided scope height and pellet you're zeroed very near peak trajectory, so you'll be bang on from about 15-30yards. Other than that, only holdovers

How in the world are you 5" low at the muzzle ?

Metric units - 5cm. It is right there at the top of the chart

Oh! Gotcha! LOL 

Now it makes sense.

 

[tsmith]

I've heard of some shooters zeroing their gun at the peak of the pellet's trajectory. That way you only have holdover aim points.

This is what I prefer to do. I find it easier and no chance of mixing up holdover/holdunders. Everything is a holdover other than dead on.

 

[nced]

Good tutorial!

Personally, I don't need to know the exact distance to the target if I know the holdovers at various "sharp focus points" at various distances.

I normally use a 30 yard zero with my HW95 springer even though the apex of the pellet flight is about 1/4" higher at 25 yards. This setup gives me two zeros, a near zero and a far zero with a bit of pellet rise between. At all distances closer or further than my near/far zero I hold high, and how high is marked on the AO or SW.

I'm certainly an oddball marking my holdovers on my AO or sidewheel since my "holdover chart" is marked directly on the wheel or AO like this........





After focusing if the pointer on my scope lines up with a plus symbol +, I hold crosshair on (why there are "two pluses" on my AO or side wheel. After focusing, if the scope pointer lines up with a dot ., I hold first lower mil dot on the target. After focusing if the scope pointer lines up with a dot-slash-dot .|., I hold between the first and second lower mil dot on the target. If the pointer lines up with stacked dots .. I hold the second lower mil dot on the target....so on and so forth.

I started using "symbol marks on the AO/SW" years ago when squirrel hunting in West Virginia because often the squirrels would move out of range when I was trying to consult my dope sheet. The only reason I started shooting field target at all was to get in some off-season "squirrel practice" so I use the same techniques on the field target course as I do squirrel hunting.