.22LR Ballistic knowledge needed...


March 27, 2009, 05:33 PM
Getting back into .22 shooting after many years..I put a Tasco Accudot on my .22LR, It sets 2.5 in. above the muzzle, shooting Federal Champion, 1280 FPS at muzzle an says 3.4 in. drop at 100yds....At 10 yds. its grouping 1.75 in. below bullseye...at 15yds, still -1.75, then at 20yds its at +.5, at 25yds its bullseye an at 40 yds its -3.0 in. I can't get over that 5yd difference between 15 an 20 yds. when its rising 2.25 in.....is this typical??? This is
going to make squirrel hunting between 15 an 20 yds. interesting!!!!!

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March 27, 2009, 05:40 PM
You need your sight (whatever the kind) to be as-low-as possible. At 2.5" above, you're creating quite an arch.


March 27, 2009, 05:41 PM
I take it to mean it is zeroed exactly dead-on at 40 yards?

And I take it to mean you plan to shoot squirrels at 15 - 20 yards?

See where this is going? :uhoh:

If you want to shoot squirrels at 15 - 20 yards, that is the distance you should zero it at.
Or at least no further then 25-30 yards, and learn where to hold under/over at shorter or longer range.

PS: The very high sight-line above the bore is compounding your trajectory problem.
A normal scope sets 1.5" above the bore, and open sights set .75", give or take a little.


March 27, 2009, 05:43 PM

go to this link and type in your info balistic coef for a .22lr should be .1340 and a 40 gr bullet. It will give you all of your bullet drop info you may need.

March 27, 2009, 05:44 PM
I think he is saying it is zeroed around 17-18 yards (somewhere between 15 and 20 he has it passing "zero" and heading up to where it is +.5 at 20) and again at 25 yards, and then 3" low at 40.

What Federal ammo are you using? I may be doing something wrong, but I can't get the numbers to work out to your results using the ballistic calculator.

ETA: I agree with woof below, it doesn't sound right.

March 27, 2009, 05:44 PM
I read the OP as zero at 25yds and down 3 in at 40 yds. Three inches is a lot for 15 yds, doesn't sound right. Also the bullet should be passing throught the line of sight twice, right? I'm only seeing that once here.

PS- Why can't I find someone to do $6 FFL transfers around here?

March 27, 2009, 05:48 PM
Oh! O.K.!
I read it six more times and finally figured it out as "at 25yds its bullseye".

Still think the sight 2.5" above the bore is causing you the problem.

It's not so much an issue on a high-velocity centerfire rifle with a very flat trajectory. (AR-15)

But it opens a big can of worms on a 22RF.


March 27, 2009, 05:56 PM
Changing sight height from 2.5" to 1.5" makes a lot of diffrence using the ballistics calculator that I posted above. I would agree that sight height is screwing you up more than anything.

March 27, 2009, 06:00 PM
jbkebert, wat do you get when zero is at 25yds and scope is 1.5 in?

March 27, 2009, 06:42 PM
woof gets a A+, yes its zeroed at 25 yds. The ammo is Federal Campion High Velocity, 36 grain, copper coated hollow point, 1280 fps at muzzle, 1020 fps at 100yds. I thought the higher scope mount could pose a problem, just didn't seem the high arc in that 5 yd. range would be that fast. I should explain this is a GSG-5 so I can't go lower with a scope. Its a fun gun first...an believe I have zeroed good enough to hit a quarter, except for that crazy 5 yds. ....I'll just back up farther or sneak in closer!!!! I just wondered if anyone had seen a .22LR with such a consistant curveball in such a short distance..

March 27, 2009, 06:58 PM
jbkebert, wat do you get when zero is at 25yds and scope is 1.5 in?

Changes Point Of Impact at 40 yards approx 3/4" so yes that is quite a bit diffent than a 1/8" change at 40 yards with same 25 yard zero and a 1.5" sight height. So yes sight height does make a diffrence in the arc of a bullet more so on a realitivly slow moving round like a .22 lr

So overall there is a 3 moa difference between 1.5 and 2.5"

March 27, 2009, 10:20 PM
I think the root of the problem was mentioned in the OP: "Tasco"

March 27, 2009, 11:08 PM

I really dont have a problem with a tasco on a .22. This is one of my favorite rifles it is very accurate despite wearing a tasco. Most of my rifles wear a leupold or a nikon at miday I cant tell the diffrence between them. At dusk there is a huge diffrence in scopes. The ranges a .22 will be used at I am very happy with the glass that is on it.

Ed Ames
March 28, 2009, 09:42 AM
30gr 1280fps 22lr w/ 2.5" scope height, 30/60 yard zero:

Range Velocity Impact Drop ToF Energy Drift
0 1280 -2.5 0 0 109 0
10 1212 -1.42 0.16 0.03 98 0.55
20 1158 -0.57 0.55 0.05 89 0.87
30 1111 0.01 1.21 0.08 82 1.39
40 1071 0.33 2.14 0.11 76 2.08
50 1037 0.33 3.38 0.13 72 2.94
60 1006 0 4.95 0.16 67 3.95
70 980 -0.67 6.86 0.19 64 5.1
80 956 -1.7 9.13 0.23 61 6.39
90 934 -3.11 11.78 0.26 58 7.8
100 914 -4.93 14.84 0.29 56 9.34

You "rise" (cross the sight plane) fast, stay within .7" of the mark from 20 to 70 yards, and drop fast after that.

You can play around with the numbers yourself here http://www.handloads.com/calc/

Try the same bullet with different scope heights (1.5", etc) and see how they stack up. What you'll find is that 2.5 is actually better for targets are between 25 and 70 yards, but 1.5" beats it for 10-60 and 0.5" irons beat them both from 0-50 if zeroed at the right distance... but zeroing irons on a .22 past 50 yards makes it *very* distance specific. So...there is no one ideal for everything and everybody.

March 28, 2009, 09:49 AM
Thanks everyone, except for anti-tasco guy....?.....Great info Ed Ames, thanks! I'll be checking this out, an see about plinking some groundhogs....my AR is better for that but .22's are fun too...

March 28, 2009, 12:22 PM
you did not mention the bbl length you had, is it the pistol type, or shorty?
also, there is no way you are allready low again at 40 yds. unless you have a very short bbl, and are no where near the muzzle speed you think you are. Also , with the shorty or pistol bbl, you are going to have an even more accute arc;
normally I would say your best ranges for squirrel getting were mentioned above, 30 to 70 yds, but your arc might be so dorky right now, that you need to stay in the front half, like 25 to 40 yds., and no more.

March 28, 2009, 12:37 PM
check this;

March 29, 2009, 10:44 AM
rangerruck....its the rifle version, around 16", bullet velocity is what it says on the box, with 39gr. bullet....I agree that velocity could be wrong, an the bullet is heavier than than the chart above...I think right now it looks like its probably hitting .0 at 17 yds an 25 yds.....next time out I am going to try .0 at 30 yds, then see where its hitting at different ranges....then I have heard CCI's, though more money have a faster velocity, an perhaps lighter bullet, an compare...I think right now I have the barrel an line of sight coming together at to close a range, the barrels on these things are also very small dia. an might have something to do with it...

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