Semi-automatics, revolvers, long guns... ask questions and offer tips on safe, accurate shooting here.
 #75522  by bluedog46
 
myopicvisionary wrote:Thank you sir, I help where I can.
so the further back you shoot once you are zeored the lower it will go?

ex if it right on at 50 yards as you got back further and further the bullet drops? I would rather hit low than over someone's head.
 #75525  by bluedog46
 
scampbell3 wrote:Here are some resources to help you better understand the physics of flight and trajectory

http://hyperphysics.phy-astr.gsu.edu/hbase/grav.html

http://www.rifleshootermag.com/2010/11/ ... tics_0303/
I am a historian. This is not something I would need a huge background in physics to use would I?
 #75528  by rosco87
 
Luckily I have a friend that was a Marine Corps PMI! He helped me sight my AR in at the range!
 #75560  by Dr. Eastwood
 
myopicvisionary wrote:Generally speaking; and your results may vary, an AR-15 firing 55gr ball zeroed at 25yds will have a POI of about 6 inches high at 100yds. At around 200yds, the POI will be approximately 9 inches high. Continuing to 300 yards the POI will be about 7 inches high, with the bullet again crossing the line of sight at 375yds.

Most average AR shooters that I have helped do better if they zero their rifles with 55gr ball at 50yds. This provides a flatter trajectory to 250yds. The POI will be around 1.5 inches low at 25yds, cross the line of sight at 50yds and be approximately 1.5 inches high at 150yds. The round will cross the line of sight again at 200yds and hit about 2 inches low at 250yds.

With the exception of Service Rifle competitors, this is a better set up for most average shooters. The ability to control a 250yd perimeter without any sight or hold adjustments is very practical.

Thanks for the "aha!" moment.


Boresighters are nice, but I've decided to waste the ammunition on practicing the dial in of my weapons. There's something so satisfying (frustrating for others) about painstakingly zeroing in. Thank god I don't press my own ammo yet. I'd be down in the basement taking hours just to perfect each batch, and that's after I take days deciding on the weight and loading.
 #75574  by myopicvisionary
 
so the further back you shoot once you are zeored the lower it will go?

ex if it right on at 50 yards as you got back further and further the bullet drops? I would rather hit low than over someone's head.
No. Perhaps I should clarify. POI is the Point of Impact.
The POI will be around 1.5 inches low at 25yds, cross the line of sight at 50yds(this is where you are zeroed) and be approximately 1.5 inches high at 150yds. The round will cross the line of sight again at 200yds and hit about 2 inches low at 250yds.

So, out to 250 yards, the round will fly a maximum of 1.5 inches over the line of sight and 2 inches below it for a total vertical spread of 3.5 inches along the length of it's flight. If only presented with a headshot, this still works well. Given that the average cranium is about 10 inches tall, aiming center of mass(between the eyes) the round should impact between the nose and the forehead. Again, the ability to control a 250yd perimeter without any sight or hold adjustments is very practical. Of course this is all dependant on the marksmanship skills of the trigger puller.
 #75598  by cslade454
 
Did you say you would be sighting in at target masters? Don't they make you use fragmentation ammo? Be aware that the info given is for military ammo and the ammo that you may have to use at target master might not perform the same.
 #75600  by myopicvisionary
 
I never said anything about Target Master. But 55gr. frangible 5.56mm ammunition is available if required for a given range.
 #75893  by GreaseMonkey
 
cslade454 wrote:Did you say you would be sighting in at target masters? Don't they make you use fragmentation ammo? Be aware that the info given is for military ammo and the ammo that you may have to use at target master might not perform the same.
I just sighted my AR in at TargetMaster last week and they gave me Federal M193. I was surprised, so I inquired and he told me you can shoot whatever, as long as you buy it there.