Posted: 10/20/2009 1:41:09 AM EDT
| Are the two different apertures set for different ranges? IE the big apperture is centered for <200 and the smaller apertures centered for 300-500 yds? |
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Nope. just one. its kind of odd. The hole is in between the sizes of the standard GI rear. the outside shape is more square then round. Takes a little getting used to. Do you have an MBUS? There are 2 apertures on the MBUS. I asked a military friend when you should use which one and he said it's not about distance but light. During the day use the small hole, during the night use the big one. |
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Nope. just one. its kind of odd. The hole is in between the sizes of the standard GI rear. the outside shape is more square then round. Takes a little getting used to. Do you have an MBUS? There are 2 apertures on the MBUS. I asked a military friend when you should use which one and he said it's not about distance but light. During the day use the small hole, during the night use the big one. Wrong answer. Another example of how well our military trains its soldiers  And I used to be one, so I speak from personal experience.
The large aperture is for ranges of 0-200 meters, the small aperture is for targets beyond 300 meters. It's hard to tell on a standard carry handle rear sight, since they do not superimpose, but if you put the two apertures together on the MBUS you will notice that the small aperture is centered a little high in the large aperture. This offset makes your bullet trajectory a little higher on long range shots when using the small aperture. Some sights (such as the ARMS 40L-SP) are designed as "same plane," which means the large and small apertures both center on exactly the same spot, in effect serving as 0-200 apertures. The smaller aperture should allow a more precise shot. |
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Nope. just one. its kind of odd. The hole is in between the sizes of the standard GI rear. the outside shape is more square then round. Takes a little getting used to. No there are two apertures. Quoted:
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Nope. just one. its kind of odd. The hole is in between the sizes of the standard GI rear. the outside shape is more square then round. Takes a little getting used to. Do you have an MBUS? There are 2 apertures on the MBUS. I asked a military friend when you should use which one and he said it's not about distance but light. During the day use the small hole, during the night use the big one. Wrong answer. Another example of how well our military trains its soldiers And I used to be one, so I speak from personal experience.
The large aperture is for ranges of 0-200 meters, the small aperture is for targets beyond 300 meters. It's hard to tell on a standard carry handle rear sight, since they do not superimpose, but if you put the two apertures together on the MBUS you will notice that the small aperture is centered a little high in the large aperture. This offset makes your bullet trajectory a little higher on long range shots when using the small aperture. Some sights (such as the ARMS 40L-SP) are designed as "same plane," which means the large and small apertures both center on exactly the same spot, in effect serving as 0-200 apertures. The smaller aperture should allow a more precise shot. Lol. I had a rifle instructor tell me the same thing about the light deal. When I explained to him about distance shooting... Instructor: "Well have you ever been in the military?" Me: "No" Instructor: "Well then you're wrong." |
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Lol. The light thing is a valid use , but again it is not the primary reason for there being two apertures. There is roughly 3 inches of difference at 100 yards. "Good" enough for grunt work, but when you are talking about precision shots at range, it is imperative to understand the POI shift. There is a reason why the large aperture has "0-2" engraved below the aperture and it is not refering to the time of day.
Page 30 from the Colt AR-15 Manual Select the aperture size for the range at which you are most liekly firing. Large 0-200m; Small 300-600m or 800m depending on type. Page 32 of the Bushmaster AR-15 Manual says the same thing. |
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Well I'm still trusting in my friend who was responsible for training troops on the firing range before he his station changed. Light > Distance As beavo stated, you can/should use the larger aperture for low light shooting, especially since you would probably not have a night shot at anything over 300 meters. But that is not what the larger aperture was primarily designed for. Do not assume that someone who serves/served in the military or police has a detailed knowledge of gunhandling, external or internal ballistics, or detailed technical knowledge of any particular firearm, to include the use of its sights. I served both as enlisted (Army Reserve) and officer (active Army) and my firearms training was limited and very basic. It wasn't until I was out of the Army for 10+ years and became a "gun person" that I realized how poor and incomplete my firearms training had been. I was so ignorant while I was in the Army that, not only didn't I know hardly anything about small arms and their proper use, I didn't know what I didn't know. Personally, I find the Army's firearms training a disgrace. As an example of this in the Marine Corps, read this heroic Marine's narrative: http://www.m4carbine.net/showthread.php?t=38540 Notice that as a Marine Rifleman MOS he was not ever trained in the basic task of how to reload in combat. Because of that he is paralyzed from the waist down. |
Ok So in other words there is a difference of "Zero" between the two apertures? Forgive me for my somewhat Laymans terms... I've never been in the military and have only attended Front Sight.  So I'm not that up on proper terminology.
But the Large Aperture is for 0-200. and the Small Aperture is slightly shifted in a vertical fashion to automatically compensate for longer range shots at 300+ Yards? Is that Correct? |
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Ok So in other words there is a difference of "Zero" between the two apertures? Forgive me for my somewhat Laymans terms... I've never been in the military and have only attended Front Sight. So I'm not that up on proper terminology.
But the Large Aperture is for 0-200. and the Small Aperture is slightly shifted in a vertical fashion to automatically compensate for longer range shots at 300+ Yards? Is that Correct? Yes, that is correct. |
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Distance? Was always tought that the big hole was used for night time and when wearing our pro-masks (gas masks) and yes I am in the Army. Okay, time to end the debate. From TM 9-1005-319-10, page 47: SHORT RANGE -
This "larger" aperature is used for 0 - 200 meters range. As shown above, the sight is set for 0 - 200 meters. This rear sight is only used when the rear sight is all the way down. In other words, the 300 meter mark is aligned with the mark on the left side of the receiver. NORMAL RANGE - The aperature is unmarked and used for most firing situations. It is used in conjunction with the elevation knob for 300, 400, 500, 600, 700, and 800 meter targets. |
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From TM 9-1005-319-10, page 47: SHORT RANGE -
This "larger" aperature is used for 0 - 200 meters range. As shown above, the sight is set for 0 - 200 meters. This rear sight is only used when the rear sight is all the way down. In other words, the 300 meter mark is aligned with the mark on the left side of the receiver. NORMAL RANGE - The aperature is unmarked and used for most firing situations. It is used in conjunction with the elevation knob for 300, 400, 500, 600, 700, and 800 meter targets. The amusing thing about this TM statement is that is says that the long range aperture is used for most firing situations. The Army's own study of WWII and Korea infantry firefights determined that most engagements were at ranges less than 150 yards. This revelation led to the proposal for a lighter, smaller caliber rifle that ended with the procurement of the M16. I doubt that has changed much - perhaps somewhat in Afghanistan. And think about it - the Army's own qualification course only goes out to 300 meters, where you would change apertures. That statement has probably gone unchallenged in the TM for 40 years
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