The shortage and rising prices of ammunition has made dedicated .22LR AR-15 rifles, and conversion kits for 5.56mm/.223 caliber AR-15 rifles very popular. Unfortunately the recent shortage of .22LR ammunition has made it hard to feed them if you didn’t already stockpile (hoard) .22LR ammunition. If you are lucky enough to have access to .22LR ammunition then the dedicated .22LR AR-15 rifles or the conversion kits for your 5.56mm/.223 caliber AR-15 rifles are fun for target shooting and plinking, and can be a great tool for teaching new shooters without the loud noise and high price of full-size center-fire ammunition.
What Distance To Zero For .22LR Ammo With AR Style 2.5″ Tall Sights:
A friend recently acquired one of Colt’s .22LR M4 rifles made by Walther Firearms and asked if I would help zero the sights at the appropriate distance. I had recently written about my research regarding What Distance To Zero Your .22LR Rifle, but I had never really taken dedicated .22LR AR-15 rifles seriously until I was asked to help zero this rifle. Any traditional .22LR rifle has its sights mounted close to the bore, and traditionally red-dots are always mounted as close to the bore as possible. I couldn’t see how you could have anything but a terrible .22LR ballistic trajectory with AR-15 sights that are 2.5″ above the bore.
Having been granted the opportunity to play with this rifle for a few days I ran a few zero distance calculations through an iPhone/iPad application called “Ballistic” using data for CCI’s 36-grain Mini-Mag ammunition, and I couldn’t believe how ignorant I had been. You can achieve very flat trajectories from .22LR ammunition and 2.5″ sights. I played with several distances and tweaked it until I found the optimum zero distance of 25 yards.
Benefits of a 25 Yard Zero:
- Note the graph above. From a distance of 13 yards from the muzzle, all the way out to approximately 89 yard, the point-of-impact of the bullet will never be +/- 1″ from point-of-aim. This means that you should be able to hit a 2″ target without any hold-over / hold-under correction anywhere within 13 yards to 89 yards!
- The highest distance above point of aim is exactly 1″ at 50 yards.
- At 100 yards you can expect your point-of-impact to be 2.37″ below your point-of-aim. To give you a visual, you will make hits below the point-of-aim less than the height that the sights set above the bore. This is pretty impressive, especially considering that you might be using a red-dot optic, such as the Bushnell TRS-25, with a 2 minute-of-angle dot (dot that appears 2″ in diameter at 100 yards).
Dedicated .22LR Rifle, or .22LR Conversion Kit?:
If you have a dedicated .22LR rifle then you have a simple task of zeroing your rifle’s optic and/or iron sights. If you have a regular AR-15 style rifle that is zeroed for 5.56mm/.223 caliber ammunition and you want to use a .22LR adaptor, such as those manufactured by CMMG, then you will have a slightly more complicated setup depending on how you have your rifle configured as the .22LR ammunition and the 5.56mm NATO ammunition have completely different ballistic trajectories. If you sights are set for one, they won’t be set for the other. Keep reading to get some ideas of how to overcome this hurdle.
Shooting .22LR Out Of A 5.56mm/.223 Caliber Rifle With Conversion Kit:
You may have a AR-15/M-4 zeroed with the 50-yard “battle-sight zero” that gives you an awesome flat trajectory with the 5.56mm/.223 caliber. You might assume that if you use a .22LR adaptor that your rifle is zeroed for the .22LR also. You would be wrong. The .22LR round is much less powerful than the 5.56mm/.223 caliber battle cartridge and has a much shorter range. If you attempt to shoot at typical .22LR distances you will find the bullets impacting much lower than the point-of-aim. That is not fun, and it doesn’t help someone who is trying to learn to shoot. So what to do? Keep reading and find the description that most closely matches your rifle’s configuration.
Carry Handle Rear Sight:
If you have a rifle with a carry handle (already “battle sight zeroed” with the 5.56mm/.223 caliber ammo as described on the AR-15 page) then the solution is easy. You can simply set up a target at that distance, move your rear sight up a couple of clicks, shoot three rounds to see where they hit in relation to your point-of-aim, and then repeat until your point-of-aim and point-of-impact are the same. It is very important that you remember where your zero setting for 5.56mm ammo is, and how many clicks you moved your sight to be zeroed with the 22LR ammo. I would advise you to write down these settings on an index card and leave it in your rifle case. Leave the rifle set to its 5.56mm/.223 caliber setting, and adjust the sights when you want to shoot .22LR ammunition. Remember, write down your settings. I can guarantee that in six months when you pull your rifle out of the closet you will have forgotten your settings.
Flat-Top Receiver With Front Back-Up Iron Sight:
You may have a rifle with a flat-top receiver and a free-floating forearm, or some other type of system that doesn’t use the traditional triangle front sight. Instead it requires a front backup iron sight. An option might be to run two forward backup iron sights. Keep in mind that most rear backup iron sights are only adjustable left and right. You can only adjust elevation with the front sight. Set up the most forward front sight for 5.56mm, and another just behind it for .22LR. When you want to shoot .22LR just drop the front forward sight (the one zeroed for 5.56mm/.223 caliber) and raise the second one (that is zeroed for .22LR).
Note 1: This setup is intended for rifles that don’t have the traditional triangle front sight tower, but rather a rail along the entire length of the top of the rifle.
Note 2: You will have to use two front sights because with 99% of the backup iron sight sets you adjust elevation with the front sight and can only make windage adjustments with the rear.
Magnified Optic:
If you have a rifle quipped with a magnified optic (a scope) with simple cross-hairs or reticle without any bullet drop compensation you will want to first set your rifle so that it is zeroed for 5.56mm. You can mark the turrets with a Sharpee marker or paint pen, or write down the values on an index card that you will keep in your rifle’s carry case. I would recommend writing down the values as the paint or ink can easily wear off and your will not have a clue of where to set your scope when you want to shoot. You can then adjust your sights to zero the rifle for .22LR. If you have a quality optic then you should be able to easily adjust your optic back and forth to match the type of ammunition that you are shooting. I would suggest storing the rifle with it set for the 5.56mm/.223 caliber ammunition as that will be the ammunition of choice should you need to employee the rifle in an emergency situation. Again, write down your settings for both types of ammunition.
If you have a rifle scope with some type of bullet drop compensation you will first want to zero the rifle scope per the manufacture’s instruction with 5.56mm/.223 caliber ammunition. Then you can set up targets at various distances and use the bullet drop compensation marking and figure out which marking coincides with point of impact with the .22LR ammunition. Example: I have a 4x ACOG. I figured out that point-of-impact at 50 yards is with the 500 meter mark, and 100 yard POI is with the 600 meter mark. Easy. Again, write it down on a card and leave it in your rifle case. You will forget your numbers. I promise.
Red-Dot Optic:
If you have a red-dot optic you may be able to mark your optic with both settings. Adjustment turrets on some optics may have numerical values that you can record, and some my not. You may have to simply record the number of clicks from one setting to the other, i.e. “7 clicks up”. Some optics adjustments may have clicks, but rather just enough friction to allow you to move the adjustment, but hopefully tight enough not to move with the rifle’s vibration. In that case you may be stuck with the “Sharpee option”. Even better than a Sharpee might be to use and engraving tool to make small marks to show each setting. Make darn sure that you have the optic set exactly where you want it before you start marking it up with an engraving tool.
Conclusion:
These are only suggestions. You are smart. Although these techniques have worked for me, you may find a solution that works even better. I’d love to hear about it.
Related Articles:
Savannah Arsenal’s Rimfire Ammunition Page
Savannah Arsenal’s Rimfire Optics & Accessories Page
Savannah Arsenal’s Rimfire Conversion Kits Page
A Great Red-Dot Optics For .22LR Rifles: Bushnell TRS-25
Bushnell Trophy Red-Dot: No-Go!
Make A New Storage Tube For Your AR-15 22LR Conversion Kit
CMMG Brand Conversion Kits For AR-15 Rifles
Gemtech’s Subsonic .22LR Ammunition = WIN!
