Grouping vs. Distance correlation

M

model14

Guest
From your experience, with no wind, if my .22LR Win 52B Re-issue Sporter shoots 1/4" groups all day at 25 yards, and 1/2" groups all day at 50 yards (the Wolf MT ammo I use has a dead flat trajectory between 25 and 50 yards), should I be able to correlate this to a 1" group at 100 yards (again, no wind)? I would think so, but it ain't happening! My 100 yard groups are more like 1-1/2 to 2".
Quite frustrating, to say the least.
Thanks,
Richard

Also, what is the approximate drift displacement of a 1000 fps, 40 grain, .22LR bullet in a 10 MPH crosswind at 100 yards. I can't us my ballistic program because I don't know the BC of the bullet (Wolf MT).

Thanks again.
 
A BC is reasonably about 0.15 for your ammo. And no, you can't expect 1" groups at 100 yds, but then there is never "no wind" and your rifle does not shoot "dead flat" from 25-50 yds unless you are shooting in deep space and even that is suspect

Brent
 
The apex of the trajectory is between 30 and35 yds so your zero is approximately the same for 25 and 50 yds.
 
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Not double - Four times the drift.

Wind drift is a squared function.
That means your bullet will drift
four times as far at 100 yards as
it does at 50 yards. And: Yup, there
ain't no such thing as a no wind
condition.
 
What Don said is correct but let me try to say it another way. The line of sight is above the barrel, naturally, and the trajectory is in the form of an arc. To be sighted in at 50 yards your bullet has passed the high point of it's ark and is on the downhill leg. At about 25 yards it is still rising and somewhere in between 25 and 50 yards it has reached it's maximum high point.

I would have guessed that your rifle would group about 1 1/4" at 100 yards. I wouldn't be surprised if there were a little breeze involved.:)

Concho Bill
 
Thank you all for your responses. Very informative.
Richard
 
I remember reading an article that said " Lapua target ammo .22lr will drift 1.2" with a constant 10 mph wind at 3 or 9 o'clock".
 
BrentD. Can you tell me what your statement is based on.
 
Here is the output of the Berger Ballistics Program for a subsonic .22LR with a .11 BC:

+----------------------------- Program Inputs ---------------------------------+
| |
+---- Bullet Inputs -----+----Atmosphere Inputs ----+-------Sight Inputs ------+
| Caliber: 0.22 inches | Temperature: 59 degrees | Sight Height: 1.5 inch
| Weight: 40 grains | Pressure: 29.92 inHg | Zero Range: 25 yards |
| G1 BC: 0.110 lb/in^2 | Humidity: 0 % | Look Angle: 0 degrees |
| G1 Form Factor: 1.073 | Density: 0.07647 lb/ft^3 | |
| MZL Velocity: 1000 fps| Wind Speed: 10 mph | |
| | Wind Direction: 3 O'clock| |
+------------------------+--------------------------+--------------------------+


+----------------------------- Program Output ---------------------------------+
Range Velocity Energy Trajectory TOF Drift
(yards) (fps) (ft-lb) (inches) (sec) (inches)
0 1000 89 -1.50 0.0000 0.00
25 955 81 0.00 0.0768 -0.31
50 917 75 -0.88 0.1569 -1.22
75 884 69 -4.34 0.2402 -2.69
100 853 65 -10.58 0.3266 -4.70

Wow, I never dreamed drift would be that much! Also, in actual practice, the drop from 25 to 100 yards is around 7", not 10 1/2".
 
Here is the same thing but with a .15 BC:

+----------------------------- Program Inputs ---------------------------------+
| |
+---- Bullet Inputs -----+----Atmosphere Inputs ----+-------Sight Inputs ------+
| Caliber: 0.22 inches | Temperature: 59 degrees | Sight Height: 1.5 inch|
| Weight: 40 grains | Pressure: 29.92 inHg | Zero Range: 25 yards |
| G1 BC: 0.15 lb/in^2 | Humidity: 0 % | Look Angle: 0 degrees |
| G1 Form Factor: 0.787 | Density: 0.07647 lb/ft^3 | |
| MZL Velocity: 1000 fps| Wind Speed: 10 mph | |
| | Wind Direction: 3 O'clock| |
+------------------------+--------------------------+--------------------------+


+----------------------------- Program Output ---------------------------------+
Range Velocity Energy Trajectory TOF Drift
(yards) (fps) (ft-lb) (inches) (sec) (inches)
0 1000 89 -1.50 0.0000 0.00
25 967 83 -0.00 0.0763 -0.23
50 937 78 -0.82 0.1551 -0.91
75 910 74 -4.12 0.2363 -2.01
100 886 70 -10.04 0.3199 -3.5
 
rkcal22 said:
BrentD. Can you tell me what your statement is based on.
Click to expand...

A BC of 0.15 and a muzzle velocity of 1163 with a 10 mph crossing wind.

I'm using JBM's website, which has been extraordinarily accurate in my experience.

Brent
 
BrentD, It was my mistake by not putting the info in at 50 yds which is just what Lapua said.
 
I'm not a person who likes to do alot of talking,you got alot of good information here to get you headed in the right direction. And besides, I'm a rank rookie compared to some of the shooters giving you advice here.
ifldned
p.s. if you think there is no wind,light up some incense sticks or a cigarette. And that's not taking into account the changes in air density, even shot in a wind tunnel. Then, there's ideal barrel temperature for the ammo you're using. It seems like the more you know, the more there is to know. That is the challenge of 22lr. My estimation is, that you have to be able to average .15 inch at 50 yards under reasonable conditions to get 1 inch groups at 100 yards under reasonable conditions. Reasonable conditions for me, probably means zero wind for you.
ifldned
the only way to test for zero outside external factors is to shoot in a 100 yard vacuum tube and I don't know anyone who has done that.
 
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If the rifle is worth a damn, the 1"-1.2" drift for a 9:00 crosswind is about right for a right hand twist barrel. That's from actual experience shooting.

Actually that type crosswind is going to move the bullet right, and down too. Providing it'sa true 9:00 oclock wind at 10 mph.
 
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