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From: bartb@hpfcla.fc.hp.com (Bart Bobbitt)
Newsgroups: rec.guns
Subject: Re: ballistics of .22lr?

Here's a reasonable set of numbers for the .22 LR bullet through 200 yards.
I've run them using Sierra's ballistic software with three different muzzle
velocities.  

   Muzzle                  Drop in Inches At:                   Velocity
  Velocity      50 yd.     100 yd.     150 yd.     200 yd.      @ 200 yd. 
  --------     -------------------------------------------      ---------

  1050 fps       4.09       17.25       40.64       75.49        827 fps

  1040 fps       4.17       17.52       41.26       76.6         823 fps

  1030 fps       4.24       17.80       41.90       77.75        817 fps

Note the difference in drop for each velocity at the different ranges.
As each fired bullet will leave the muzzle at a different velocity, the
greater the muzzle velocity spread, the greater the vertical spread is
at each range.  For example, a muzzle velocity spread of 20 fps gives a:

  * 0.15-in. vertical spread at 50 yards.

  * 2.26-in. vertical spread at 200 yards.

A 20 fps spread in muzzle velocity is about what the best match-grade
ammo produces.  Over-the-counter hunting/plinking ammo will easily have a
velocity spread twice that amount.  This means the vertical shot stringing
with that ammo will about double over what the table shows.  A 4.5-in.
vertical spread at 200 yards due to velocity spread implies the ammo isn't
too good for accuracy.  

Then one needs to add the normal shot dispersion due to differences in
bullets as they ain't all perfectly balanced as they spin going down range.
Bore and bullet quality effect this and can easily cause up to 4 more
inches of group size increase at 200 yards.  Combining this 4-inches of
dispersion with that caused by velocity spread totals up to a 200-yard
group of over 6 inches.  

Smallbore competition at 200 yards uses a target with a 4-inch diameter
10-ring.  The best rifles and ammo will shoot groups at 200 yards about
1 inch diameter.  At 100 yards, that same rifle/ammo combination will shoot 
groups about 3/8ths of an inch at 100 yards.  Typical hunting rifles with
regular ammo produce groups at least five times as big. 

So, 200 yard accuracy is dependent on several things.  Given the right
stuff, the .22 LR bullet can do very well at that range.

BB

 
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