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Posted: 9/20/2004 11:56:43 PM EDT
[#1]
A2 always has 8/3, detachable is supposed to always have NM or 6/3.
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Posted: 9/20/2004 11:57:45 PM EDT
[#2]
My M4 doesnt have a carryhandle...
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Posted: 9/21/2004 12:06:17 AM EDT
[#3]
I'd be worried if they were using the wrong rear sight bases, the 6/3 is a carry handle thing not an M4 thing.
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Posted: 9/21/2004 12:52:17 AM EDT
[#4]
According to pages 0011 00-2 and 0011 00-7 of the following manuals it is: Army TM 9-1005-319-10 Air Force TO. 11W3-5-5-41 Navy SW 370-BU-OPI-010 Operator's Manual For Rifle, 5.56 MM, M16A2 W/E (1005-01-128-9936) (EIC:4GM) Rifle, 5.56 MM, M16A3 (1005-01-357-5112) Rifle 5.56 MM, M16A4 (1005-01-383-2872) (EIC:4F9) Carbne, 5.56 MM M4 W/E (1005-01-231-0973) (EIC:4FJ) Carbine, 5.56 MM M4A1 (1005-01-382-0953) (EIC:4GC) Headquarters, Department of the Army October 1998 From page 0011 00-2 25 Meter Zeroing Procedure (Cont) Battlesight Zero c.:
From page 0011 00-7 25 Meter Zeroing Procedure (Cont) Battlesight Zeroing Adjustments (Cont) 3.:
Edited to correct second quotation from manual. |
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Posted: 9/21/2004 12:56:09 AM EDT
[#5]
Sharkman, thats because the M16A2/M16A3 have an 8/3 carry handle and the M4/M4A1/M16A4 have a 6/3 detachable carry handle. The difference in zeroing procedure between the M16A4 and M4/M4A1 is to compensate for their different trajectories.
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Posted: 9/21/2004 12:57:39 AM EDT
[#6]
M4A3/M16A4 (detatchable handle)-> 6/3
M4/M4A1/M16A2 (fixed handle) -> 8/3 |
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Posted: 9/21/2004 1:03:26 AM EDT
[#7]
By quoting the above manual, what I am trying to say is that I believe that all military M4 carbines, regardless of model, should have the 6/3 elevation settings due to the weapon's sight radius and velocity/trajectory differences with the 14.5" bbl.
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Posted: 9/21/2004 1:08:52 AM EDT
[#8]
All detachable handle guns should have it. Putting an 8/3 on a detachable handle will prevent it from being used on a rifle. |
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Posted: 9/21/2004 2:00:16 AM EDT
[#9]
I guess what bothered me the most were dealers selling 14.5" bbl. "M4 uppers" that had fixed carry handles with the 8/3 sight. Also, most detachable carry handle 14.5" bbl. uppers at the show had the 8/3 sight as well. IMO, if your trying to build an M4gery as authentic as possible, you should insist on the 6/3 sight. As I understand it, the 6/3 sight is necessary because of the differences in the bullet's trajectory coming out of a 14.5" bbl. as opposed to a standard 20" bbl for an effective zero procedure. However, and please correct me if I'm wrong, the M16A4 has a 20" bbl. and a full sight radius. If so, why does the manual call for a 6/3 and not an 8/3; if sight radius and trajectory are the cause for the difference in zero settings? I don't understand why, if only because the handle is detachable, the zero settings are different. There has to be a better reason when many detachables have the 8/3 sight. I look forward to your thoughts. Edited for typographical errors. |
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Posted: 9/21/2004 2:08:17 AM EDT
[#10]
This whole argument is inane. Does anyone really use those numbers to dial in at distance? They are way off, and pretty useless for this purpose on ANY rifle. Learn your dope for your rifle and ammo and be done with it.
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Posted: 9/21/2004 2:25:29 AM EDT
[#11]
The issue here is strictly for authenticity. If done correctly, those numbers do give a good reference. I've put in a few hundred hours at the range and that comment was, as you put it, "pretty useless". |
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Posted: 9/21/2004 2:26:13 AM EDT
[#12]
Colt made very few M4s with A2 uppers, these uppers had the 8/3 elevation wheels. All new Colt M4s have detachable carry handles and 6/3 so that's why the TM is written that way saying M4s have 6/3. No reason to write a TM for a few 1000 rifles that you will never see.
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Posted: 9/21/2004 2:30:42 AM EDT
[#13]
The question seemed to be one of compatibility with barrel length for accuracy - not authenticity. My point was that neither one will be much use numbers-wise. However, I bow to your superior internet marksmanship skills  .
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Posted: 9/21/2004 2:40:38 AM EDT
[#14]
Again, no need to be a smartass when someone is seeking an opinion. 
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Posted: 9/21/2004 2:41:54 AM EDT
[#15]
Thank You. |
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Posted: 9/21/2004 3:38:01 AM EDT
[#16]
Sharkman629, Is there some particular reason you quoted my post? Instead of referencing the highly flawed marksmanship manuals why don't you look it up in the 23&P? You'll see that the carry handles on the M4 and the M16A4 are identical part numbers. The uppers differ because of the feed ramps on the M4. |
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Posted: 9/21/2004 8:14:24 AM EDT
[#18]
As others are also trying to point out, the difference has nothing to do with bullet trajectory, but everything to do with physical room to move the knob. Clearly, since the 14.5 inche barrel and 20" barrel use the same sights, the numbers can't be top precise - even if supposedly calibrated for a certain barrel length with a certain round. On top of that, most of us do not shoot the green tip GI ammo that it WOULD be calibrated for if it ever really was. I may have come off as a smartass, but your comment of "hundreds" of hours brought that out of me. Many others here, including myself, have put far more than that both behind the trigger and pulling pit duty in just any one particular shooting season. You asked for answers, and - between all the posts here - you have recieved them. They are: 1) The difference is based on whether the carry handle is removable or not, NOT the barrel length. 2) The numbers are of little practical use anyway. 3) I believe you will find that, on either M4s or M16s, that the rear sight moves the same amount per click on both, bullet trajectory be damned. |
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Posted: 9/21/2004 3:11:43 PM EDT
[#19]
While I agree that the range numbers are of limited utility barring actual firing, and corresponding notation, at those ranges, the ranges line up very well mathematically when using M855.
I would bet that the reason for the "6" instead of the "8" on the carry handles is that is the break point between the two (M4 and A2) trajectories. Beyond 6 the trajs are too different for one part to correct for both. |
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Posted: 9/21/2004 4:00:20 PM EDT
[#20]
Where's Troy when you need him
The reason why a detatchable carry handle is 6/3 and a fixed carry handle is 8/3 isn't because a fixed carry handle can shoot longer than a detatchable carry handle. It's because of the design of the two. A detatchable carry handle uses a shorter screw because the screw of a fixed carry handle would have to goe through the top of the receiver. When Troy shows up he'll explain it better than I can 
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Posted: 9/21/2004 5:47:18 PM EDT
[#21]
just a thought my rock river a2 came with the 6/3 rear sight don't know why you would need more elevation
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Posted: 9/21/2004 8:02:42 PM EDT
[#22]
Vinnie and alpha15 are correct. The threaded portion of an A2 rear sight base is too long to use on a detatchable carry handle - it will stick out the bottom. Rear sight bases for removable carry handles are thus made shorter to fit. Because these shorter bases cannot "come up" as far as the full length A2 rear sight base, the range is limited to 600 meters instead of 800. The top of the EL wheel (the marked part that is held on by the little allen screw) comes in two flavors - one is marked 8/3 with range markings (4 5 6 etc) for a 20" barrel, and one marked 6/3 with range markings (3 4 5) for carbines. Right?
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Posted: 9/21/2004 8:19:09 PM EDT
[#23]
I could be wrong, but I believe that the thread pitch on the screw is different between the 6/3 and 8/3. This is why one full revolution raises the sight from 300-800m on the 8/3 and 300-600m on the 6/3. Otherwise though, if you go from 300 to 600 m. on both sights, the rear sight should move the same amount of distance up relative to the receiver.
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Posted: 9/21/2004 8:41:21 PM EDT
[#24]
Oops, wrong window.
There is no mechanical reason Colt couldn't have made the sight go to any height they wanted. They did change the thread pitch and the thickness of the RSB from the A2 style.. |
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Posted: 9/21/2004 9:13:05 PM EDT
[#25]
Yeah, I was at the gunshow and you asked me about the rear sights. I *thought* the 6/3 thing was a carry handle only deal, but I wasn't really sure so I didn't say anything. Umm, on reading your post, I note that you state that you were under the impression that a 14.5" barreled upper with M4 handguards required the 6/3 rear sight drum. Does this mean I get in trouble for putting carbine handguards on a Bushy 14.5 W/permanently attached Phantom? Now I guess we both know that 6/3 sights are only for detachable carry handles. Cool 
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Posted: 9/22/2004 6:11:46 PM EDT
[#26]
Tweak:
I quoted your post because you said the 6/3 issue "wasn't an M4 thing." I should have remembered the M16A4 had the detachable handle. I looked it up and your right, the part numbers are identical. Adam_White Sorry we both got upset. My use of "a few hundred hours" was only express that I am, by no means a newbie on the range. I said that when I took offense at my issue being called "inane" and being told to learn my dope. I know the numbers aren't exact, but they do provide a decent reference for iron sights. My desire for them is authenticity alone and I wanted to know the reason behind the differnce, especially if was for a reason to compensate for ballistical differences between barrel lengths. No disrespect meant, just thought your response was a little strong. 123whisper: Did I also ask you about the feed ramps? Sorry, I asked a lot of people about the sights and can't remember which dealer you were. Were you in the back area of the show floor? If we talked about this site as well, I remember you. To All: Thanks for all of your points as you guys, as always, have cleared my brain's doublefeed. |
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