From: toby@u.washington.edu (Toby Bradshaw)
Subject: Re: [RIFLE] shooting in heat haze: how?
Organization: University of Washington, Seattle

In article <33vlrm$6f5@xring.cs.umd.edu>,
Chris Beasley  <cb1p+@andrew.cmu.edu> wrote:

#Rail gun?
#Bag gun?
#
#Please elaborate!

A rail gun is a mechanical return-to-battery rifle used in the
unlimited class in benchrest or for accuracy component testing.
It is often built on an aluminum I-beam (the "rail").  The
tracking system is so accurate that re-sighting between shots
is not necessary.  Think about what that entails -- if the muzzle
of a 24" barrel is displaced 0.001" from its previous position
the bullet will be off 0.150" at 100 yards.  Ted Larson just
shot 5 5-shot groups at 100 yards with his rail gun and the
groups *averaged* 0.147" (NW unlimited championship).  That's
how well a rail gun can shoot even without looking through the
scope!  Most rail gunners shoot "heads up", watching the wind
flags and paying no attention to the sight picture.

Bag guns are 10.5# (sporter and light varmint), 13.5# (heavy
varmint), or unlimited-weight benchrest rifles shot off
malleable sandbags.  No rigid guidance system capable of
returning to battery after firing is permitted in the varmint
and sporter classes.  Bag guns are fast to move from record to
sighter target and back, which helps when the wind is switching.
Rail guns can be fired very fast because no re-sighting is required,
so most rail gunners try to run their shot string in a single
wind condition (an excellent plan for any shooting, BTW).  In
mirage the rail gunners usually take home the tinware because
they're not shooting at a moving target!

-Toby Bradshaw
toby@u.washington.edu