Sighting In a Scope for Squirels

"Sighting in a Scope for Squirrels"
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I'm just grateful that all the squirrels in my neighborhood have not learned how to properly sight their scopes. It's bad enough as it is that I have to run quickly from my car to my door without them also being able to hit what they are shooting at.

Damn them squirrels.
 
Sweet Shooter, the absolute drop of a standard velocity .22 long rifle bullet is about 4 inches at 50 yards and about 17 inches at 100 yards.

Absolute drop is how far below the bore axis a bullet falls on its way to the target. It can be calculated by multiplying 16.1 ft by the time of flight in seconds squared, or the lazyman way of going back to the JBM ballistics calculator and inputting zero for sight height and 1 yard for zero. It won't accept zero yards as an input for zero range.

With a 4 inch absolute drop, it would be impossible to have a 50 yard first zero unless the scope was mounted at least 4 inches above the bore.
 
B.L.E. Thanks for the clarification. I kinda remember now why I don't shoot 22 very much, probably 'cause I could never hit anything–ha ha!. I thought that 22LR would do better than than. I know the apps aren't perfect, but they are probably better than me at guesstimating. I have always thought of the curve/trajectory like the way a good fishing pole loads with a good fish on—the drop off compounds towards the end. I thought we were good out to 50 yards. but I guess not.

I have never eaten Squirrel but am told they are very tasty. They must be okay to eat as America survived on them for a while during and after the war... and probably some do today. I feel some Trail Boss reloads are in the offing. Rabbits just started too!

-SS-
 
Oh yeah, I remember from my childhood we used to eat em fried like chicken. Not that much different than rabbit. :)
 
I sight my 22's at 50 yds, aim a little low closer targets, aim a little high for farther targets.

I'm not real proud of it now, but as kids, we shot running rabbits in fields using the old battleship firing routine:

Fire one round, observe impact, adjust elevation/lead, fire for effect until rabbit sunk or disappeared over the horizon.
 
My squirrel gun is sighted at 25 with Aguila subsonic and I can make head shots all day long at 50. i don't always aim for the head b/c the little buggers have a habit of not sitting still:D. Point is, sighted at 25 is plenty accurate for them. I don't shoot past 50 usually but make body shots then.
 
Three inches high or low works as a definition of point blank range for cenerfire rifles and large game but would be a clean miss on a squirrel. It's the smallness of a head shot vital zone on a squirrel that makes the point blank range of a scoped 22 between 15 and 55 yards with SV ammo. Also, because of the smallness of the vital zone, you get the phenomenom of being closer than point blank range. When you make a head shot at a squirrel that's only 3 yards away, you gotta put the crosshairs slightly over the squirrel's head or you will shoot under it.
 
Thank you eZero. That calculator has been added to my favorites.

You can find a list of published velocities for all kinds of .22 S,L, and LR ammo at this site.
http://www.ruger1022.com/docs/22lrballistics.htm

Instead of assuming a .123 BC, I experiment with different BC numbers until the calculator closely matches the published 50 and 100 yard velocities. With CCI standard velocity target ammo, a .112 BC seems to fit the best.
This gives a calculated velocity that's slightly low at 50 yards but slightly high at 100 yards.
 
I sight my Marlin 60 for 50 yards with CCI mini-mag for squirrels. Hold a little low for shots a little closer and a little high for shots a little farther. The nice thing about this setup is that as long as you aim center mass at anything closer than 50 yards and you will score a hit. Works for me. Also any tree rats within 10 yards get the GSG 1911. Keeps it interesting.
 
JBM doesn't give a graph (which frankly isn't all that useful anyway) but does have a database of Bullets and Ballistic Coefficients from damn near everyone.

http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

All this is meaningless unless you start with good data, and a very important piece of the puzzle (particularly for a .22 LR, pretty much the opposite of "flat shooting") is sight height. Measure the center-line of the bore to the center-line of the scope.
 
emcon5 wrote:
JBM doesn't give a graph (which frankly isn't all that useful anyway) but does have a database of Bullets and Ballistic Coefficients from damn near everyone.
Click to expand...

emcon5,
I just plug the JBM no.s into an excel spreadsheet I made. I plot the trajectory on 1 axis and the bullet energy on a 2nd axis.
 
I guess I just sight my rifles in at 50 yards then practice shooting stuff at different distances to see how they work. The variation between the powder levels of different brands of ammo and even among the same brand of ammo makes the scientific charts more theory than actual fact. It's be nice if all ammo fell into these formulas but it never seems like to work exactly right. The science is good but the actual reality of the situation is different. It's good to know the data listed here though. It does give you a general idea how things should work and will work if you get really consistent ammo.
 
.22 LR Scope zeroing: Easy follow up questions

Thanks for the info and dialogue above. Very helpful.

Regarding BLE's data on bullet-drop at various yardage, does this formula change if one is shooting up into trees or otherwise not shooting with the barrel horizontal to the ground? i.e., is a yard a yard or does gravity have a different effect if shooting "up?"

Also, zeroed at 50 yards, when shooting at 75 yards I was a bit more than 1" low, so was looking for exactly how much higher to aim at that distance. Placing the top of the lower heavy post on the bulls eye was too much compensation so hit too high. Without hashmarks/mil-dots in my scope I experimented with an unscientific method of aiming up by 1 "squirrel head" at 75 yards and 2 squirrel heads at 100 yards. Any other such rules of thumb out there, or do I need to just get a scope with hash marks?
 
I have always zeroed the scope at 25 yards for .22's, long range shots I have a tendency to want to hold a little high and it works perfectly.
 
One thing im trying to understand is does the bullet actually rise a little from the muzzle height, then come down to zero then drop lower and lower?

It rises above muzzle height because the muzzle is pointed ever so slightly upwards (more so with increasing distance), but it doesn't rise above an imaginary straight line drawn down the barrel and infinitely out into space.

What it certainly does rise above is your line of sight - an imaginary straight line drawn from your eye to the rear sight and then the front sight (for irons) or through the scope optics, and to the target. As others have said, it cuts above this line once on the way up and again on the way down. The second of those two is your zero range. Somewhere in between is the maximum trajectory height, slightly closer than halfway between you and the zero range.

So long as the maximum trajectory height is less than half the height of the squirrel, you'll be good to hold in the centre and nail him at any distance out to zero and slightly beyond (until the bullet drops BELOW the line of sight by the same margin). This is the benefit of high velocity, and probably is what drove the success of the .17 HMR.
 
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