AR-15 Zeros and Trajectories

**hrt4me** · 06-22-12, 17:43

great info, thanks!

**ParanoidCivilian** · 07-18-12, 22:18

The instructions say they are for 8/3, mine are 6/3? What should I do?

**ddw736** · 07-18-12, 23:33

if you are using a 11.5 inch barrel, I would recommend sighting in at 25 yards. 11.5 are for CQB and have no practicle use past 200. 200 is really pushing it for an 11.5. Our motor units carry 11.5 on the bikes and we sight them in at 25yd. 11.5 lose a lot of velocity regardless of what ammo you are using. You have to pick the right rifle for the job. If you are in an urban environment, look across the street and depending on where you live, that could be between 25-50 yards. I would never use a 11.5 unless it was an entry. I would stick to 14.5 or 16 for urban.

**Failure2Stop** · 07-23-12, 00:57

Originally Posted by ddw736

if you are using a 11.5 inch barrel, I would recommend sighting in at 25 yards. 11.5 are for CQB and have no practicle use past 200. 200 is really pushing it for an 11.5. Our motor units carry 11.5 on the bikes and we sight them in at 25yd. 11.5 lose a lot of velocity regardless of what ammo you are using. You have to pick the right rifle for the job. If you are in an urban environment, look across the street and depending on where you live, that could be between 25-50 yards. I would never use a 11.5 unless it was an entry. I would stick to 14.5 or 16 for urban.

A 25 meter zero actually makes 0 to 200 meter engagements (specifically the 0 to 25) more difficult than the other zeroing methods (50/200 or 100 meter POA/POI zeroes). Take a look at the trajectory charts in this thread and take a look at the linked thread for more information:
https://www.m4carbine.net/showthread.php?t=107572

Originally Posted by ParanoidCivilian

The instructions say they are for 8/3, mine are 6/3? What should I do?

For 6/3 marked sights you will need to be able to fully reach 6/3(- 4).
That is 4 full clicks "below" 6/3. Lots of folks will have their sights set so that they can go to (-5), but set it on (-4) to ensure that they have the detent fully rested.

The reason is that the 6/3 marked sights have half of the adjustment as the 8/3 marked sights per click, therefore you need to use twice as many clicks to travel the same distance.

**rob_s** · 07-23-12, 04:43

Originally Posted by ddw736

if you are using a 11.5 inch barrel, I would recommend sighting in at 25 yards. 11.5 are for CQB and have no practicle use past 200. 200 is really pushing it for an 11.5. Our motor units carry 11.5 on the bikes and we sight them in at 25yd. 11.5 lose a lot of velocity regardless of what ammo you are using. You have to pick the right rifle for the job. If you are in an urban environment, look across the street and depending on where you live, that could be between 25-50 yards. I would never use a 11.5 unless it was an entry. I would stick to 14.5 or 16 for urban.

Dear God. That just sounds like a whole truckload of bad advice and bad information, largely gleaned from folklore, out of date theory, and Internet reading.

What happens when one of those motor cops arrives at a parking lot and starts winging shots out across the open prairie at some similarly-armed bad guy?

With modern ammunition choices the maximum effective range of the 5.56, even out of shorter barrels, is greatly increased, and even if it isn't a hit is still better than a miss.

There is no reason for a 25 yard zero that good training can't overcome.

**swedeboy** · 07-25-12, 00:56

Great info

**GUNSLINGER67** · 07-26-12, 08:04

Excellent info Molon , thank you .

**bronson224** · 08-06-12, 12:08

Okay, so this is my first time on the forum and my first post. From reading through this a little bit it looks like for a 50yard zero i want to be about an inch low at 30yd right? the reason I ask is cause i just got a new AR and i want to sight it in for 50Yds but my local range only has a 100yd and 30yd rifke range and they wont let you place targets at any other distances. Ive never shot the rifle let alone with my optic on it so i have no idea where its going to be hitting at any distance yet. Thanks for any help and sorry if this isnt the right places for the question.