AR-15 Zeros and Trajectories

[T2C]

How would one find a near zero for there rifle before trying to site it in if they want a 200 yard far zero? Is it possible to do a 30 yard near zero or something similar?

I usually start at 25 yards to rough zero a rifle, then shoot at 50, 100, 200 and 300 yards to verify my zero. Your question prompted me to throw a couple of extra rifles in the Jeep yesterday, so I could check my points of impact at 30 yards for myself. My rifle and carbine are both zeroed at 200 yards with M193, which was verified before firing at 30 yards. I rezeroed with M855 before firing at 30 yards. All groups fired with iron sights from the prone position at 200 yards ran from 3-1/2" to 6" center to center. Note: I don't carry a concrete bench around with me, so I always zero from the prone position.

Conditions-sunny, 80 degrees, winds 190 degrees relative at 5-10 mph. All shots were fired between 10:00 A.M. and 12:00 P.M.

AR-15 rifle with 20" barrel:
M855 ball velocity measured 3017 fps at 15 feet from the muzzle
M193 ball velocity measured 3238 fps at 15 feet from the muzzle

AR-15 carbine with 16" barrel
M855 ball velocity measured 2946 fps at 15 feet from the muzzle
M193 ball velocity measured 3065 fps at 15 feet from the muzzle

The center of the SR-21 target repair center was placed 15" above the ground and 10 shot groups were fired from the prone position. The barrels were fouled. The groups at 30 yards were 1" with M193 and 3/4" with M855. POI was measured from the POA to the center of the shot group.

Rifle POI:

M855 POI - -1-1/4" at 30 yards
M193 POI - - 1" at 30 yards

Carbine POI:

M855 POI - 3/4" at 30 yards
M193 POI - 1" at 30 yards

And before the question is asked the answer is no, I did not take a camera to the range.

If you are going to zero at 30 yards and are firing the same ammunition, this should give you a starting point.

[thopkins22]

Keep in mind that the closer you shoot your zero, the more you're going to be off at your intended zero. Conversely, if you can't hold a good group at 200, there's no point to attempting it. Personally I like to zero 1"-1.5" high at 100, and then shoot the rest of my yardages and walk the ground and see what's actually happening.

With that said, I have a target designed to put you on a fifty yard zero by shooting at 25 yards, if you like I'll email it to you. I just don't really recommend it unless you absolutely positively don't have access to a real rifle range.

At 25 yards your POI should be roughly an 1.1" lower than your POA.

As T2C is inferring, all of this 50/200 is VERY dependent on load and rifle combination. But it'll be close enough that the differences likely won't matter too much...but you truly will not know until you actually shoot it, walk the ground, and see what happens.

[T2C]

noliver,

I suggest logging your observations and shooting results for each trip to the range. If for no other reason, you will know what sight adjustments to make if you are zeroed for M855 and all you can find on short notice for a three gun match is Wolf 55g.

[Gray Ghost]

I bought a KAC 300 meter BUIS for my 10.3" AR-15.
I want to zero it for 300 meters with 62gr M855 ammo on a 100 yard rifle range.
How high should my rounds be hitting on the target at 100 yards?
Thanks

[Caduceus]

I bought a KAC 300 meter BUIS for my 10.3" AR-15.
I want to zero it for 300 meters with 62gr M855 ammo on a 100 yard rifle range.
How high should my rounds be hitting on the target at 100 yards?
Thanks

My rifles seem about 2-4 inches off at 100, depending on ammo; best to just zero at 25meters and adjust from there, as the 25/300 is the current "battle sight" distance. Then, once zero'd at 25m, you can see about where you'll be at 100 yards.

[Gray Ghost]

My rifles seem about 2-4 inches off at 100, depending on ammo; best to just zero at 25meters and adjust from there, as the 25/300 is the current "battle sight" distance. Then, once zero'd at 25m, you can see about where you'll be at 100 yards.

I don't have access to a range that measures anything in meters. They may have a 20 yard line for pistols but I'm not sure.
More than likely for rifles, they've just got the range marked at 50 and 100 yards.

[T2C]

I don't have access to a range that measures anything in meters. They may have a 20 yard line for pistols but I'm not sure.
More than likely for rifles, they've just got the range marked at 50 and 100 yards.

A 50 yard zero is roughly a 200 yard zero. Point of Impact at 100 yards will run from 1-1/4" to 2" high depending on ammunition and barrel length.

[Failure2Stop]

I bought a KAC 300 meter BUIS for my 10.3" AR-15.
I want to zero it for 300 meters with 62gr M855 ammo on a 100 yard rifle range.
How high should my rounds be hitting on the target at 100 yards?
Thanks

The 300 meter BUIS doesn't have to be zeroed at 300 meters, and doing so is going to severely limit your applicable envelope with that barrel length.
However, if that's really what you want, the POI will need to be about 5"-6" high at 100 with a 10.3 barrel and M855.

[Gray Ghost]

The 300 meter BUIS doesn't have to be zeroed at 300 meters, and doing so is going to severely limit your applicable envelope with that barrel length.
However, if that's really what you want, the POI will need to be about 5"-6" high at 100 with a 10.3 barrel and M855.

Thank you for answering my question.

[jeffreywt]

Since this thread is sticky, I'll necro to mention that this post is top shelf. Thanks so much for the effort.