Why zero the red dot at 36yd? Why not 37yd, or 35yd, or 36m, or 25yd, or 41yd, or 6.367yd? Why so specifically 36yd?
- Thread starter Jigstick
- Start date
...the zeroing range was based on specific ammunitions ballistics, i.e, FPS, trajectory path.
So maybe not white 36yd. I’ll chrono the loads. Figure out some dope. And figure out what zero range will allow me to have the least dispersion between point blank and “X”.
....skip to Chapter 8, speaks to use and purpose of the 33Y/36M distance.....
Chapter 8 of the cited Marine Rifle Marksmanship manual:
"Prezero Sight Setting for the Rifle Combat Optic A zero established at 33 meters/36 yards is not as accurate as a zero established at 100 meters/ yards. Therefore, a prezero sight setting is established at 33 meters/36 yards and the weapon is zeroed at 100 meters/yards.
Correct. But what specific ammunition, ballistics, etc. If you don't know when/where/how/why it exists, then how do you know when/where/how/why to use it correctly?
It is a good, question, and a very good answer exists for it.
It was, however, not some "goofball" as you suggest. 36yd exists for a very specific reason, to be applied in a very specific set of circumstances. And while I and a small handful of others know, as I suspected, virtually no one on here throwing out advice knows why.
Like so many things in such circles, everyone does something because everyone else does it, and no one in either group has any real idea why. It is the definition of herd mentality.
That quote is specific to the RCO, BTW. It does not absolutely apply to anything else.
If you are talking about me, you could not be more wrong.he wants you to try to keep guessing what's in his pocket. It makes him feel superior.
I keep dancing around giving an answer intentionally, because I want it revealed by the lack of valid answers to the 36yd question, just how little knowledge all of these people giving out advice actually have.
BTW: Someone has already given the answer. Or at least the source to find the answer. It will now take some effort to find it, but that is how things are learned; With effort. That is how I learned it. I did not sit around and wait for some expert on a forum to tell me, I did the research and learned for myself.
It could be said that you are correct in at least some aspect of your statement: Because I put forth the effort to learn, I am now superior in my knowledge set on the subject. I guess you got me after all.
Bro, you left out the part about using two different segments of the reticle for that.
For those who might not be familiar with the ACOGs with the chevron reticle, the top of the post portion of the reticle is used at the 33/36 distance and the tip of the red chevron is used at 100.
The 36 yard zero was originally nothing more than a field expedient distance (near zero) for obtaining a 300 yard far zero when using a 20” barrel firing M855.
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............Considering it has worked exactly as I planned................
What does the history or knowledge set of anyone else on this thread have to do with your misrepresentation of a quote from a USMC document?
You really shouldn't push that much effort or energy towards me, I am not that important in your life. After all, this is just an internet forum.
bingo.Bro, you left out the part about using two different segments of the reticle for that.
For those who might not be familiar with the ACOGs with the chevron reticle, the top of the post portion of the reticle is used at the 33/36 distance and the tip of the red chevron is used at 100.
The 36 yard zero was originally nothing more than a field expedient distance (near zero) for obtaining a 300 yard far zero when using a 20” barrel firing M855.
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It usually doesnt take this long. Most operators I ran with over the years werent shooters. They could shoot and move well but they rarely understand anything outside of their bubble. The ones that do are generally really good.
There's even a logical fallacy that describes them (the worshippers) very well: appeal to authority
It wasn't a guy, it was the US Marine Corp. It is basically answered above, but I will give an answer in a slightly different form.
The old carry handle sights on the M16/M4 had a lowest setting of 300m with the small aperture. The 300m/small aperture zero was used as the standard zero distance on these rifles. But there were circumstances where this was not a practical distance, such as:
1) The facility did not have a 300m/yd range.
2) The weather/other conditions did not allow the practical use of a 300m/yd range
3) A preliminary sight-in (i.e. "getting on paper) was desired
4) For many possible reasons, is was deemed unnecessary to zero on a 300m/yd range. (I was never in the Marines, but I have been told that many non-combat personnel would perform their zero training at 36yds, though this is at best second-hand information from me.)
In these instances, the Marines began using a 33m/36yd zero in the above instances. For a 20" M16 with M855 ammo and a 300 zero, this is the POA/POI distance while the bullet is going up on its trajectory. Thus, in theory, a zero at 36yds is also identical to a zero at 300. The 36yd zero therefore is nothing more than an expedient way to zero an M16/M855 rifle system when a 300 zero is not practical/available/desirable. It gives a close approximation to a 300 zero, but not an exact one.
So unless you have a 20" barrel shooting M855, with a sighting system that does not go below 300, a final zero of 36yds likely does not make sense. There are viable reasons to use a 36yd zero on other systems, but just using it because:
1) That is how you did it in the military. And the military always does things the best way possible.
2) Everybody around me is doing it, so it must be the right way
3) Some dude on some internet forum told you it was a good idea.
4) Somebody at the range that said he was very operater-ry told you to do it
None of these are good reasons.
NOTE: The newer USMC flip-up BUIS is different, cranks down to 200m, but still applies a similar zeroing principle. The M4 is 14.5", has a much lower muzzle velocity, and therefore the 36yd zero is not applicable or sensible. By the same physics, neither does a 36yd zero on any 16" rifle likely make sense. And yet...........
...actually, in that USMC document it states the 33Y/36M prezero process is used for all 3 sight systems, RCO, BUIS and Iron Sights, with the caveat that "zeroing" is to be conducted at distance.
BLUF, chrony your ammo, run the numbers in a ballistic calculator, then confirm the results returned at the indicated distances.
It does indeed say that. However, that is not the part I was referring to concerning the systems discussed in the document. Nor does it mean that any part of the statement is valid for any system outside of those discussed in the document.
Within the Document: The quote in question is directly taken from the section concerning the RCO, just I stated. The particular part he highlighted in blue:
Therefore, a prezero sight setting is established at 33 meters/36 yards and the weapon is zeroed at 100 meters/yards.
Is not valid for any of the iron sights discussed in this document, because none of these iron sights have a 100m/yd setting. The RCO has a BDC reticle calibrated to a 100m zero, thus the portion in blue IS valid for the RCO. So in the context of this USMC document, this section of cut/paste is not valid to anything but the RCO, as I stated.
Outside of the Document: The entirety of the statement may or may not be valid, depending on a slew of factors concerning the rifle, ammo, optics, and intended purpose of the system. It is only certain to be valid for the M16/RCO system discussed in the document. Also as I already stated.
Furthermore, this document is nearly 10 years old, and likely has lost significant validity in today's USMC. In fact, the recommended zeroing for the flip-up BUIS discussed here was changed to a 25m prezero at some point after this document. At least as an option. There is a mark on the sight for the 25m zero, and I have some of the actual documentation and a zeroing target for one.
Plus, this BUIS is now being phased out for something else. I don't know exactly what is replacing it, but the new VCOG the Marines adopted seems to have a different BUIS with it. And Ebay is suddenly full of the ones in this document from surplus.
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