My new RDO should be delivered by Christmas. It will be installed on my new Aero Precision AR15 with 18-inch SS fluted bbl and rifle length gas system. The primary purpose of this AR15 is home defense. I wanted to keep the gun light and the 4oz RDO will also provide a quick sight acquisition. I have run several calculations using a 55gr bullet at 3100fps muzzle velocity with JMB trajectory chart. I believe that the red dot sight should be sight-in at 50yds. The bullet would only be 1 inch low at 25yds, 1 inch high at 75 yds and 2 inches high at 100yds. The second zero would be at about 250yards. I would like to hear opinions from anyone who has a similar AR15 with a red dot sight primarily used for " social adjustment"
- Thread starter charliebrown1999
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I sight everything in at 100 yard battle zero. Dial-up, or use BDC from there.
My 14.5" 5.56 with 55gr ammo, the 100 and 200 yard zero's are nearly exact. I sighted it in at 100, and with the 3x fixed power scope, I aim dead on the 5" gongs at 200, and it hits them every time.
My 14.5" 5.56 with 55gr ammo, the 100 and 200 yard zero's are nearly exact. I sighted it in at 100, and with the 3x fixed power scope, I aim dead on the 5" gongs at 200, and it hits them every time.
Your calculations are very close. However, I would reverse your process. Zero hard and accurate at 200. This will give you holdovers very close to what you described. You will need to run your rifle at cqb distances to get your close holdovers. House or room distances will be more than 1” of drop. I ran this zero on my 3g rifle for years. Basically from 40 to 225 yards, you will be no more than 2” high or low from your RD. 300 will be a simple 10” low. You will have to get farther holdovers with other points on your reticle, but my eyes can’t see much past 300 without a little magnifying anyway. This is a VERY good zero that some people just can’t wrap their head around. It is so simple. CQB, you have to hold over regardless of your zero distance, then 40 to 225, put the dot on it and shoot it!
I find most times when it comes to AR's, doing what Proctor does is never a bad idea:
Frank Proctor’s 50 Yard Zero at 10 Yards
This recent video (below) from Frank Proctor at Way of the Gun and Trigger Time TV is excellent. In it, Proctor talks about why he uses the 50 yard zero, how to achieve a 50 yard zero at 10 yards, …
jerkingthetrigger.com
Zeroing Target – 50/200 Yard Zero at 10 Yards
You may remember Frank Proctor’s method for achieving a 50/200 yard zero at 10 yards with your AR-15 that was mentioned here a few months ago. I have been putting it to good use. It is a very…
jerkingthetrigger.com
There are a number of different zeroes that would work for what you need.
People think this stuff is new but it's not. Knowledgeable hunters have been using the concept of point blank range for a given target size for decades since hunting scopes almost never had any BDC or references of any sort other than the intersection of the reticles in the middle.
What I would do is decide the diameter of a target size that will suit your needs. In your case, a circle that encompasses the entire upper thoracic cavity will do. Then use your ballistic solver to figure how which zero distance will maximize the range at which bullet trajectory never falls outside the radius of your target zone. That is known as max point blank range.
I use JBM ballistics which has a function to calculate zero at MPBR.
A 200m zero works pretty good for real work guns but I always confirm at 200m instead of a 50m zero and how that is good (it's almost never exactly on).
Thats a lot of barrel for home defense, a 7.5” 300AAC with a pistol brace or 11.5 5.56 with 77gr would serve far better. What you have is great for some 600 yard work.
Dont get me wrong im a fan of 18” plus barrels and like your choice just not for a home defence situation. That said for home use i zero at 7 yards,, and a holographic or the simple iron sites as in pics, and The reason being from my former years in law-enforcement, he average police shooting occurs at 7 yards or less so unless you’re indoor surroundings exceed 21 feet in any direction a 25 yard or 75 foot zero would be far too excessive. Any type of rifle in the home is essentially replacing a pistol and so should be treated as such.
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