Tilting your rifle...bullet flight path? - Page 2

Boncrayon · March 3, 2015, 06:02 PM

It's really all about gravity and NOT sight line. To tilt a rifle, you still have to account for the forward energy of the bullet as it is leaving the muzzle and the gravity force from the vertical ground.

Bart B. · March 3, 2015, 10:58 PM

????????

g.willikers · March 4, 2015, 10:11 AM

Has no-one mentioned the effect of the spinning of the earth?
Are you guys slipping or what?

Bart B. · March 4, 2015, 01:48 PM

No, they haven't

It's effect is negligible up to 1100 to 1200 yards. It's masked by other ballistic and atmospheric variables to difficult to easily correct for. No top ranked long range competitor I know of ever gave it a thought. I never did, either.

At longer ranges, it does have an effect. US Naval shipboard gunfire control computers calculate for it. As they also do for deck tilt (cant, for land lubbers). I operated and maintained one of those monsters in the late 1950's. All done with simple high school trig functions. Smaller numbers are used for rifle fire but the same stuff happens.

At target range, the muzzle points somewhere above the aiming point. The bullet drops some distance straight down below that point to hit where the site's aim at (microscopic coriolis and spin drift amounts ignored). If the rifle's canted to one side, that point where the muzzle points rotates in a circle to one side and a little below level from its original position. The bullet now drops straight down the same amount below that point. Bullets drop the same amount if the rifle's canted 90 degrees, but now from a point straight out horizontally from the rifle. If the muzzle pointed 35 MOA above the aim point originally, then canted 90 degrees, the muzzle now points 35 MOA to one side and bullet drop will be the same from that point down.

A 100% trig function. Calculate your own:

http://www.jbmballistics.com/cgi-bin/jbmmpm-5.1.cgi

Read this article for a good explanation in detail:

http://home.kpn.nl/jhhogema1966/skee...#_Toc449514675

March 3, 2015, 06:02 PM	#26
Boncrayon Senior Member Join Date: March 24, 2008 Posts: 920	Tilting your rifle...bullet flight path? It's really all about gravity and NOT sight line. To tilt a rifle, you still have to account for the forward energy of the bullet as it is leaving the muzzle and the gravity force from the vertical ground.

March 4, 2015, 10:11 AM	#28
g.willikers Senior Member Join Date: September 28, 2008 Posts: 10,442	Has no-one mentioned the effect of the spinning of the earth? Are you guys slipping or what? __________________ Walt Kelly, alias Pogo, sez: “Don't take life so serious, son, it ain't nohow permanent.”

March 4, 2015, 01:48 PM	#29
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	No, they haven't It's effect is negligible up to 1100 to 1200 yards. It's masked by other ballistic and atmospheric variables to difficult to easily correct for. No top ranked long range competitor I know of ever gave it a thought. I never did, either. At longer ranges, it does have an effect. US Naval shipboard gunfire control computers calculate for it. As they also do for deck tilt (cant, for land lubbers). I operated and maintained one of those monsters in the late 1950's. All done with simple high school trig functions. Smaller numbers are used for rifle fire but the same stuff happens. At target range, the muzzle points somewhere above the aiming point. The bullet drops some distance straight down below that point to hit where the site's aim at (microscopic coriolis and spin drift amounts ignored). If the rifle's canted to one side, that point where the muzzle points rotates in a circle to one side and a little below level from its original position. The bullet now drops straight down the same amount below that point. Bullets drop the same amount if the rifle's canted 90 degrees, but now from a point straight out horizontally from the rifle. If the muzzle pointed 35 MOA above the aim point originally, then canted 90 degrees, the muzzle now points 35 MOA to one side and bullet drop will be the same from that point down. A 100% trig function. Calculate your own: http://www.jbmballistics.com/cgi-bin/jbmmpm-5.1.cgi Read this article for a good explanation in detail: http://home.kpn.nl/jhhogema1966/skee...#_Toc449514675 Last edited by Bart B.; March 5, 2015 at 08:09 AM.

March 3, 2015, 10:58 PM	#27
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	????????