Artillery Rear Sight Offset???

[biffj]

Originally Posted by FNorm

Being a long range, high power shooter, let's talk ballistics for a minute. Can a 9mm go 800 meters? Sure. Can it do so accurately? Prolly not. I regularly shoot .308 and 30.06 at 600 yds, and a 6.5 X 284 at 1000yds. Planning reloads, you have to keep the bullet supersonic til it hits. Generally 1100fps. Muzzle velocity on the .308/ 30.06 is in the 2500-2700fps range to do this, with a 175-190 gr. bullet. The 142 gr. bullet leaves the 6.5/284 at 3200+. A 9mm 115-125 gr. muzzle velocity is 11-1250?

A bullet that slows to subsonic will start to tumble, and weave around. It is still dangerous, and will do harm. But I think the French Helmet thing was propaganda. Probably worked as the treaty made them stop making artilleries.

FN

for most rifle bullets there is a definite correlation between the transition from supersonic to subsonic and the tumbling of bullets. It all has to do with stability and long thin bullets which fly well at long distance are not terribly stable when the spin slows and the buffeting of the transonic shockwave starts. That is the biggest cause of the inaccuracy at long range. I've seen the same issues with my long range stuff like the .50 cal and the 20mm. However, for pistol bullets the same doesn't hold quite so true. There is some instabilty at the point where the bullet goes transonic and the shockwave moves back in front of the bullet but it is nowhere near as extreme or destabilizing to the short bullets fired from handguns. I'm not trying to say that the 9mm parabellum is very accurate at 900 yds but its not quite so bad as you seem to think. When we dug bullets out of the sand dune at 900 yds the 9mm bullets had always hit point first and showed some impact damage like having the plating scratched off by the sand at impact. The same was not true of the .223 stuff we fired at the same range. We normally found the bullets lying pointy end toward the shooter and they were so nice and undamaged that they could almost have been reloaded, except for the rifling grooves of course. The 9mm bullets also kicked up a pretty good cloud of sand at that range while the .223's were nearly undetectable. The whole point I'm trying to make here is that the 9mm is not a good round for long range shooting if your intent is to hit a particular target but for "volley fire" type shooting it can be pretty effective and dangerous to the attacker. Accuracy is good enough to get them in the ballpark too....

Frank