A high-powered rifle bullet could go 3 miles easily. You’d have to point the weapon up to nearly a 45 degree angle though. A bullet fired at or near the horizontal can only travel as far as its velocity can carry it while it is falling toward the ground at 32 ft/second squared.
The sound of a rifle being fired could carry two miles, especially if the wind is right. However, it is likely that the bullet would arrive at the point of impact long before the sound did. Subsonic bullets, again, won’t get far if they are fired at or near the horizontal. Bottom line is it is serious misconduct or seriously bad range construction if a shooter fires over or through a backstop.
I make no judgement about whether the round that hit the golfer came from the range. However, if the club isn’t supervising its members shooting practices, then they are wrong and liable. Sometimes people do stupid things on a range if standards are not enforced, especially by and among the shooters themselves.
I have been on ranges where it is impossible to fire over the backstop from the firing points. This is done with overhead cover so as to preclude that possibility. I do not know if the range in question is constructed that way.
3,600 meters is 2.23 miles.
M16/A2 shoots a 5.56mm/.223 cartridge:
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Describe the ranges for the M16/A2 Rifle.
* Maximum Range - 3,600 meters
* Max Effective Range for a Point Target - 550 meters
* Max Effective Range for an Area Target - 800 meters
http://www.armystudyguide.com/content/army_board_study_guide_topics/m16a2/m16a2-study-guide.shtml
This link has a velocity listed for a .223 round at maximum range:
.223 Remington (55 gr SP BT)
Muzzle Velocity 3240 ft/s
Maximum Range 3875 yard, 2.20 mile
Impact Velocity 545 ft/s
http://askville.amazon.com/shooting-gun-bullet-travel/AnswerViewer.do?requestId=3928729