Often at the range I have had to explain to people what Minute of Angle (MOA), and Milradians mean. Today I was reading about the Nemo .300 Win Mag ARs and I found they had a nice explaination of the two in their rifle’s manual.
Quoting from the Nemo manual:
Mils and MOA differ from an inch because they are angular, not linear, measurements. An inch equals an inch no matter how far away it is.
What is MOA? MOA stands for minute of angle. There are 360 degrees in a circle and each degree is divided into 60 minutes. If we round to the nearest 1⁄100 of an inch, at 100 yards 1 degree measures 62.83 inches. One MOA, 1⁄60 of that, measures 1.047 inches. While 1 MOA at 100 yards equals 1.047 inches, at 200 yards it equals 2.094 inches (2 x 1.047). To calculate MOA at any distance, multiply 1.047 by the distance in yards and divide by 100.
What is a MIL? MILS (milliradians) is another angular measurement. There are 6.2832 (π x 2) radians per circle. There are 1,000 mils per radian so, there are 6,283.2 mils in a circle. There are 21,600 MOA in a circle, so a little quick division determines there are 3.4377 MOA per mil. At 100 yards, 3.4377 MOA equals 3.599 inches (3.4377 x 1.047). Rounded up, one mil equals 3.6 inches at 100 yards. A mil is so large, it’s broken into tenths in order to make precise adjustments. If you have a riflescope with mil adjustments, each click equals 1⁄10 mil. A tenth of a mil equals .36 inch or .9144 centimeter at 100 yards. Since 1⁄10 of a mil is an angular measurement, it will be slightly larger at 100 meters than at 100 yards because 100 meters equals 109.361 yards. At 100 meters, 1⁄10 of a mil equals .9999 centimeter. Practically speaking, 1⁄10 of a mil equals 1 centimeter at 100 meters. Because mil, like MOA, is an angular measure, the length it represents increases with distance. For example, 1 mil at 100 yards equals 3.6 inches and 7.2 inches at 200 yards. To calculate how many inches are in a mil at any distance, multiply 3.6 times the distance in yards and divide by 100.
Their manual does an excellent job of summing up what the two are. Sometimes I have a hard time explaining this to new shooters.
Then question then arises, “Which is better?” Neither, they are two options with various pros and cons. If you shoot paper targets at known distances, MOA is usually preferred. You can measure or see how many inches of adjustment you need on paper, convert number of inches to minutes, then convert adjustment that to clicks. Mil adjustments are usually 1/10 mil per click, making the math similar to when you use SI units(metric system).
Both systems work well, the only main suggestion I have is don’t use a scope that mixes the two. It used to be common to have scopes with a Mildot reticle, and MOA turrets. This can make the math a pain.
If I am shooting at 565 yards, and I am using a MOA scope and I see I am impacting a foot low I know that.
1 foot = 12 inches.
1 MOA at 565 yards is about 5.6 inchs.
So 2 minutes of adjustment would be about 11.2 inchs, so I would want to come up about 2 and 1/4 MOA.
If I am using a Mildot reticle and a 1/10 mil turret, I can use my Mildot to measure the angular distance from my point of aim to my impact. So if I see its 1.2 mils low, I dial up 12 clicks.
But when I used a mixture of the two, I usually have to break out my calculator.
So once again I am shooting 565 yards, and I see I am impacting 1.5 mils low. I have to convert that mil measurement into MOA. So if I am in a hurry I would times 1.5 by 3.5(rounding) which is a little over 5 minutes. 5 and 1/4 MOA to be exact. Then I would dial that 5 1/4 MOA into the turrets of my scope. The math conversions can quickly get annoying. This is why I got rid of the Super Sniper 10x scope I had, and something I find irritating when I use my Leupold TS30-A2.
It doesn’t really matter if you use MOA or mils, but which ever you use, train to be competent and confident with them.
The BATFE has released an open letter posted here.
OPEN LETTER ON THE REDESIGN OF “STABILIZING BRACES”
The Firearms and Ammunition Technology Division (FATD), Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) has received inquiries from the public concerning the proper use
of devices recently marketed as “stabilizing braces.” These devices are described as “a shooter’s aid that is designed to improve the single-handed shooting performance of buffer tube equipped pistols.” The device claims to enhance accuracy and reduce felt recoil when using an AR-style pistol.
These items are intended to improve accuracy by using the operator’s forearm to provide stable support for the AR-type pistol. ATF has previously determined that attaching the brace to a firearm does not alter the classification of the firearm or subject the firearm to National Firearms Act (NFA) control. However, this classification is based upon the use of the device as designed. When the device is redesigned for use as a shoulder stock on a handgun with a rifled barrel under 16 inches in length, the firearm is properly classified as a firearm under the NFA.
The NFA, 26 USCS § 5845, defines “firearm,” in relevant part, as “a shotgun having a barrel or barrels of less than 18 inches in length” and “a rifle having a barrel or barrels of less than 16 inches in length.” That section defines both “rifle” and “shotgun” as “a weapon designed or redesigned, made or remade, and intended to be fired from the shoulder….” (Emphasis added).
Pursuant to the plain language of the statute, ATF and its predecessor agency have long held that a pistol with a barrel less than 16 inches in length and an attached shoulder stock is a NFA “firearm.” For example, in Revenue Ruling 61-45, Luger and Mauser pistols “having a barrel of less than 16 inches in length with an attachable shoulder stock affixed” were each classified as a “short barrel rifle…within the purview of the National Firearms Act.”
In classifying the originally submitted design, ATF considered the objective design of the item as well as the stated purpose of the item. In submitting this device for classification, the designer noted that
The intent of the buffer tube forearm brace is to facilitate one handed firing of the AR15 pistol for those with limited strength or mobility due to a handicap. It also performs the function of sufficiently padding the buffer tube in order to reduce bruising to the forearm while firing with one hand. Sliding and securing the brace onto ones forearm and latching the Velcro straps, distributes the weight of the weapon evenly and assures a snug fit. Therefore, it is no longer necessary to dangerously “muscle” this large pistol during the one handed aiming process, and recoil is dispersed significantly, resulting in more accurate shooting without compromising safety or comfort.
In the classification letter of November 26, 2012, ATF noted that a “shooter would insert his or her forearm into the device while gripping the pistol’s handgrip-then tighten the Velcro straps for additional support and retention. Thus configured, the device provides the shooter with additional support of a firearm while it is still held and operated with one hand.” When strapped to the wrist and used as designed, it is clear the device does not allow the firearm to be fired from the shoulder. Therefore, ATF concluded that, pursuant to the information provided, “the device -2- is not designed or intended to fire a weapon from the shoulder.” In making the classificationATF determined that the objective design characteristics of the stabilizing brace supported the
ATF hereby confirms that if used as designed—to assist shooters in stabilizing a handgun while shooting with a single hand—the device is not considered a shoulder stock and therefore may be attached to a handgun without making a NFA firearm. However, ATF has received numerous inquiries regarding alternate uses for this device, including use as a shoulder stock. Because the NFA defines both rifle and shotgun to include any “weapon designed or redesigned, made or
remade, and intended to be fired from the shoulder,” any person who redesigns a stabilizing brace for use as a shoulder stock makes a NFA firearm when attached to a pistol with a rifled barrel under 16 inches in length or a handgun with a smooth bore under 18 inches in length.
The GCA does not define the term “redesign” and therefore ATF applies the common meaning. “Redesign” is defined as “to alter the appearance or function of.” See e.g. Webster’s II New College Dictionary, Third Ed. (2005). This is not a novel interpretation. For example ATF has previously advised that an individual possesses a destructive device when possessing antipersonnel ammunition with an otherwise unregulated 37/38mm flare launcher. See ATF Ruling 95-3. Further, ATF has advised that even use of an unregulated flare and flare launcher as a
weapon results in the making of a NFA weapon. Similarly, ATF has advised that, although otherwise unregulated, the use of certain nail guns as weapons may result in classification as an “any other weapon.”
The pistol stabilizing brace was neither “designed” nor approved to be used as a shoulder stock, and therefore use as a shoulder stock constitutes a “redesign” of the device because a possessor has changed the very function of the item. Any individual letters stating otherwise are contrary
to the plain language of the NFA, misapply Federal law, and are hereby revoked.
Any person who intends to use a handgun stabilizing brace as a shoulder stock on a pistol (having a rifled barrel under 16 inches in length or a smooth bore firearm with a barrel under 18 inches in length) must first file an ATF Form 1 and pay the applicable tax because the resulting firearm will be subject to all provisions of the NFA.
If you have any questions about the issues addressed in this letter, you may contact the Firearms and Ammunition Technology Division at email@example.com or by phone at (304) 616-4300.
Max M. Kingery
Firearms Technology Criminal Branch
Firearms and Ammunition Technology Division
One of the above pictures show a keyhole, another one shows a cloverleaf.
While I was in the Marine Corps, the terminology had at some point gotten mixed up. Our instructors in boot camp would call cloverleafs keyholes. I forgot about that till much later.
About two years later, one of my peers, was reading a book on aircraft maintenance. It stated that to check the barrels on the machineguns on the aircraft, you set up a plywood board and fire at it. If more than half the rounds keyholed, you would replace the barrel. This guy was astonished. He came to me and asked me why would you replace a barrel when half the rounds are going into the same hole? So I had to explain what a keyhole really is.
A keyhole is when a bullet strike the target sideways. Usually because it is unstabilized and tumbling. The top picture shows two 75 grain .223 match bullets fired out of a M16A1 barrel at 25 yards. Notice that both struck the target sideways. However both struck very close to point of aim.
A cloverleaf is where you have multiple touching impacts. The bottom target shows five 9mm rounds fired at 7 yards. The bottom cluster of three shots would be called a cloverleaf.
I’m not a fan of Beretta, but I find this ad of theirs awesome.