Originally posted by Icarus Rising
I get you. Its the bullet's path of travel due to the inclination of the barrel versus the line of sight to the target.
Sighting in a scope after one shot is a pretty good trick, the old one click equals a quarter inch at 100 yds extrapolation. You just need to be good
with math, know your scope and your weapon, and be on the paper with the first shot, right?
Correct about being on the paper with the first shot although that doesn't happen many times.
Due to most sighting in of scoped centerfire rifles is done at 100 yards.
You can go backwards on the ballistic tables and adjust the scope - once the rifle is sighted in - to approx 2" high over what the scope is aimed
That gives you a very close to right on the money at 200 yards.
Some flat shooters kicking out a high stepping bullet, say 3800' per second may be sighted in say 1 - 1 1/2" high at a hundred yards and other
rifles shooting a heavier bullet at perhaps 2800 fps may be sighted in at 2 1/2 - 3" high and be close to right on at 200 yards.
The trick with the one shot sighting in is to set the target at 25 yards.
Shoot off a bench rest and aim for dead center on the target.
You'll want to use a target with 1" grids.
A rifle that's 2" high and 2" to the right at 100 yards will show 1/2" high and 1/2" right on the 25 yard target.
Just click in the appropriate adjustment on your scopes adjusters and a shot at the 100 yard target should be right on.
A useful trick to save ammo.
Seen more than a few times guys who were shooting at 100 yard targets take quite a few shots to just get on the paper.
If you don't reload and use factory loads, that can get expensive real quick.
Off the subject a bit from military rifles, but with military or civilian firearms accuracy is paramount.
My last rifle - purchased many years back - was a Ruger Model 77 bolt action heavy barrel in 22-250 caliber.
Scope was a Leupold 12 power.
First shot at 100 yards was 2" high - right where I wanted the elevation - and 1/2" to the right.
Interesting and it says a lot about the capabilities of modern firearm and scope manufacturers.
Getting back to the military caliber question, one reason the military went to the 223 was to lighten the load carried by riflemen.
308 (7.62 NATO) and the earlier 30-06 rounds weigh quite a bit more than the little 223's.
A second reason was that the 223 was fairly destructive on limbs and the thinking was that it was better to seriously wound an enemy soldier than it
was to kill him.
Killing him took one soldier out of action.
Wounding him took three soldiers out of action because it takes a couple of guys to carry the wounded soldier and his rifle to safety and medical
I think weight savings in the ammunition dept. will come from caseless or plastic cased ammo.
Some weight could be saved as well by developing a recoil-less rifle design and very lightweight materials could be used.
A 5# rifle is not out of the question.
Some competition rimfire (22 LR and the like) rifles are using carbon fiber barrels with steel liners.
My suggestion would be to go to 6mm (243 caliber) in a caseless round and fire it from a lightweight rifle.
You could raise bullet weight from the 223's about 55 grains or so to 85 grains in the 6 mm with minimal weight penalty.
The harder hitting bullet would still do maximum damage to limbs and such.
I understand the military has experimented with very fast moving bullets and launching systems.
On the order of 8000 fps.
Compare that with the considered pretty fast speed of the abovementioned
22-250 that launches at 3800 fps with reasonably mild powder loads.
Other civilian 22 caliber centerfire rifles launch at over 4000 fps, touching on 4200 fps at times.
There is a 204 caliber round out there.
It's pretty destructive on ground squirrels, prairie dogs, coyotes and the like.
The good part about it is that recoil is so mild you can remain on target after the shot is fired and see where it hits.
A decided advantage for a rifleman in a long range firefight.
Even so, if the 8000 fps designs ever see the light of day, it'll be a whole new world in the firefight area....
(Edited to add a missing line.)
[edit on 19-4-2006 by Desert Dawg]