With the popularity of the AR platform and the .223/5.56 round I thought it would be a good idea to review the trajectory of the round and common sighting ranges. Being a high velocity round the trajectory is relatively flat within a few hundred yards – past 400 the drop-off is significant.
There are several philosophies on sighting in the AR and what range in best. Here are a few examples:
50 Yard Zero – Sighting in the AR to be on the money at 50 yards is extremely popular and typically what I do. Why? Because at 100 yards I will be hitting about 1.5″ inches high and at 200-225 I will be back on the money. This provides excellent accuracy from 0 out to past 250 yards with little if any compensation especially if we are talking about shooting man-sized targets.
This is by far the most popular method used for sighting in an AR.
100 Yard Zero – Not a bad option at all. With a zero of 100 yards, the .223/5.56 round will impact approx 3/4″ low at 50 yards and around 2.25″ low at 200 yards.
25 Yard Zero – I don’t care at all for sighting in at 25 yards. When zeroed at 25 yards the round will also be zeroed at 300 yards. This strategy does not provide much of an advantage unless longer range shooting is planned. The problem is between 25 and 300 yards where either the rear sight has to be adjusted for elevation while shooting or english used.
All these numbers are relative and depend on specific barrel lengths, loads, and barrel rifling.
What about 10.5″ barrels?
AR pistols are all the rage with the most common barrel length being 10.5″ inches. With a shorter barrel, a loss of velocity occurs which affects trajectory. The shorter barrel does not affect accuracy(look in the comments for disagreements). With the lower velocity and change in trajectory – I still like the 50 yard zero. If you are on at 50 yards – you’ll be approx 1″ high at 100 – and 3″ inches low at 200 yards. Your mileage may vary.
Stack ’em high and stack ’em deep!!
JR
 *   *   *   *   *   *   *   *   *   *   *   *   *
Not much to disagree with here.. it’s all fact..
I will say that an AR pistol of .223/5.56 is not for long shots.. but high capacity, high penetration and maneuverability in close quarters (car or truck cab etc.) Long configurations you have to debark to have what you need.
Much has been said about .223 vs 5.56 NATO and whether they will fire in either configured weapon. Most modern rifles will accommodate either.. However be aware NOT ALL through. Ensure both will operate in whatever you have, or at least know about it. The .223 is about 60,000 PSI where NATO 5.56 is 50,000 PSI. The cartridge dimensions are only slightly different and either config will chamber the cartridge. I have noticed slight differences in targeting on the tail end of the shot.
You can usually tell by looking at the cartridge and or head stamp.
Visually a .223 brass is uniform in polished brass color, whereas the 5.56 by DOD/Military specification is “unburnished”. The end of the cartridge near the bullet is shaded darker than the body of the brass portion of the cartridge. That is a milspec requirement. This occurs when the brass is resized down to the correct dimension to chamber a 5.56 bullet. The military wants the shading to persist if sold to DOD military 5.56 round. Makes it easy to identify. Same hold true for .308 vs 7.62×51. Both imply specific capabilities.
As JR said it’s an excellent round and fairly ubiquitous. Being able to accommodate both rounds widens your options, in the event of scarcity.
Have some fun!
GG58
I have just one thing to say, that AR Saint pistol is freaking SEXY! Oh and I agree with the article completely, nice chart showing the trajectory though. Very valuable information well laid out.