View Full Version : 50 yard Zero
Hello, Everyone
I've been doing research one which Zero would be best overall for a M4; so far I have gotten alot of people are saying to go with a 50 yard Zero vs the U.S Army's Standard 25 yard zero.
I found the following data: (from AR15armory.org)
" If You want to shoot 15-100y for most of your shooting. With your current zero you will be ~6" high at 100y depending on barrel length and ammo. Since 25y is your zero, everything beyond that will be high, ~2.2" high at 50y, 6" at 100y, ~8" high at 150y and ~9" high at 200y. Your numbers will be worse than a Mil zero (numbers given by TS above) because that zero target you used is really a 31y zero because it requires adding elevation to zero (the z setting on the elevation knob on the carry handle iron sights, 8/3 or 6/3+ 1) and then backing down to 8/3 or 6/3 for your battlesight zero.
If you use a 50y zero, then you will be ~1.2" low at 25y, dead on at 50y, ~1.5" high at 100y, ~.5" high at 200y. See these charts for a very good description and recommendations from the Army Marksmanship Unit. AMU zeroing data "
http://www.usaac.army.mil/amu/ServiceRifle/M16-M4%20data.pdf
http://www.eotech-inc.com/documents/M16A4-M4MWS_EOTech_LBS_Target.pdf
I'm Using a Eotech 511, on a yankee hill raiser; iron sights are alerady zero'd. Just trying to figure out how to get setup here.
Does anybody know if they make 50 Yard laser boresight Target Like the Eotech one ? I know some People in the Army/Military have a AKO account with different documents or files for Targets i heard.
I am a big fan of the 50 yard zero. My dept uses them on our patrol rifles and it is the best zero for a carbine IMO.
No need to mess with your sights from 0-300 yards. 400 yards requires a bit of hold over but not to bad.
ForTehNguyen
09-30-10, 14:28
hmm the max rise on a 25 yard zero is 7"? Other charts I've seen say its a rise of 10"
I like the 50 yard zeros myself
What would be the best way to setup a M4 for a 50 yard zero? Can't seem to find any laser boresight targets for 50 yards for red-dots/eotechs
devilsdeeds
09-30-10, 14:41
Setup a bullseye target at 50y and shoot it...
There's been a few threads on this, checkout the optics subforum.
Here's a good thread and a pdf to start you out.
https://www.m4carbine.net/showthread.php?t=35064
http://grburnett.us/guns/ImprovedBattlesightZero.pdf
RogerinTPA
09-30-10, 14:57
Hello, Everyone
I've been doing research one which Zero would be best overall for a M4; so far I have gotten alot of people are saying to go with a 50 yard Zero vs the U.S Army's Standard 25 yard zero.
I found the following data: (from AR15armory.org)
" If You want to shoot 15-100y for most of your shooting. With your current zero you will be ~6" high at 100y depending on barrel length and ammo. Since 25y is your zero, everything beyond that will be high, ~2.2" high at 50y, 6" at 100y, ~8" high at 150y and ~9" high at 200y. Your numbers will be worse than a Mil zero (numbers given by TS above) because that zero target you used is really a 31y zero because it requires adding elevation to zero (the z setting on the elevation knob on the carry handle iron sights, 8/3 or 6/3+ 1) and then backing down to 8/3 or 6/3 for your battlesight zero.
If you use a 50y zero, then you will be ~1.2" low at 25y, dead on at 50y, ~1.5" high at 100y, ~.5" high at 200y. See these charts for a very good description and recommendations from the Army Marksmanship Unit. AMU zeroing data "
http://www.usaac.army.mil/amu/ServiceRifle/M16-M4%20data.pdf
http://www.eotech-inc.com/documents/M16A4-M4MWS_EOTech_LBS_Target.pdf
I'm Using a Eotech 511, on a yankee hill raiser; iron sights are alerady zero'd. Just trying to figure out how to get setup here.
Does anybody know if they make 50 Yard laser boresight Target Like the Eotech one ? I know some People in the Army/Military have a AKO account with different documents or files for Targets i heard.
300 meter zero is the standard Army Zero. The 25 yard zero is used to approximate a 300M zero, for time saving purposes. Same as for the 50M or yard zero is used for a 200 (225) yard zero. It's damn close, but you should always zero at the furthest distance as a final check.
MrMilspecer
09-30-10, 15:31
What would be the best way to setup a M4 for a 50 yard zero? Can't seem to find any laser boresight targets for 50 yards for red-dots/eotechs
Start close 10-20 yards get on the paper then move back some more shoot repeat before you know it your sighted at 50 yards. Sandbags and a makeshift bench are what I use for the fine tuning. You can draw a dot on a peice of paper or cardboard and aim at it. No need for special targets. With good optics i like to shoot a hole then aim for it to make little groups...fun
Rmplstlskn
09-30-10, 15:32
I know Larry Vickers does (or did) advocate for a 100yd zero and a few weeks back I was trying to find the posts that discussed why he chose 100yds over the much more common 50yds but never found the thread. I'm sure he has a good reason...
PREP threads for his classes say to have it zeroed at 100yds or prepare to know and answer why you chose another zero... (Cross-examined by Vickers doesn't sound fun)...
I zero at 50yds because I like that trajectory path for my possible needs and it is easy to zero at 50yds... My eyes can see the details of a 50yd target much clearer than I can a 100yd target...
As for laser boresights and all that stuff, forget it... Don't need it... Shoot at 25 yards and get that centered and an inch or so low... Then move to 50. You will be on paper and not too far off. Adjust as needed...
When putting on a new sight or scope, I seperate the upper and remove the BCG... I then peek through the barrel at some object and while holding the upper still I adjust the sight/scope to that object. Then you move to the 25yd paper... Really easy, honest...
Rmpl
ForTehNguyen
09-30-10, 15:41
dont need a boresighter. In my experience irons will be on paper at 50 yards on new builds. If you have a red do, zero the irons first, then you can then just cowitness the red dot with the irons. Get it as close as you can then zero the red dot and fine tune as necessary.
If you dont have irons with a red dot, you can pull the upper off and look through the barrel and then where the red dot is pointing and you can at least get it on paper that way.
Rmpl,
I'm taking a Vicker course in November and was reading the same thing about the 100 yard zero. I currently have mine zero'd at 50. I may change it for the class and then switch back afterwards. That's called being chicken and having to worry about being grilled as to why I went with a 50yd zero:D
ForTehNguyen
09-30-10, 15:48
100 yard zero has the max bullet rise at around 100 yards, anything after that is a holdover. Bullet basically rises and kisses its peak at near 100 yards before coming back down
I doubt Vickers will hound you over it, zeroes are personal preference.
I don't think he would give me much grief either. However, from what I've read here 50yard zero is what I will stick with. When I first went in the Army mid 80's 25/300 was what we were told and how we zero'd. 50yr/200m seems more practical over all though.
RogerinTPA
09-30-10, 19:23
I know Larry Vickers does (or did) advocate for a 100yd zero and a few weeks back I was trying to find the posts that discussed why he chose 100yds over the much more common 50yds but never found the thread. I'm sure he has a good reason...
PREP threads for his classes say to have it zeroed at 100yds or prepare to know and answer why you chose another zero... (Cross-examined by Vickers doesn't sound fun)...
I zero at 50yds because I like that trajectory path for my possible needs and it is easy to zero at 50yds... My eyes can see the details of a 50yd target much clearer than I can a 100yd target...
As for laser boresights and all that stuff, forget it... Don't need it... Shoot at 25 yards and get that centered and an inch or so low... Then move to 50. You will be on paper and not too far off. Adjust as needed...
When putting on a new sight or scope, I seperate the upper and remove the BCG... I then peek through the barrel at some object and while holding the upper still I adjust the sight/scope to that object. Then you move to the 25yd paper... Really easy, honest...
Rmpl
His former Unit (SFOD-D) used it (100M Zero) and it suited there purposes. As long as you can justify your zero, and you can hit accurately with it (and knowing your hold overs at varying distances), I'm sure LAV won't mind.
StraightShooter7
09-30-10, 19:55
Sighting in at 50 yards puts you dead on at 50 (obviously) and about 225 and you are never more than 2 inches off.
IMO, it really is the best way to go.
http://img.photobucket.com/albums/v284/AMMOTECH/STA72786.jpg
Target at 25 yards with Aimpoint zeroed at 50.
Point of aim is the red dot; point of impact just over an inch low.
.
+1 to the 50 yard zero! I just sighted my new Aimpoint M4S in at 50 yards and was very pleased with the results. I sighted in using the bench of course but once I got it zeroed I started shooting while standing. Lets just say that I need more practice shooting off-hand like that. I've been watching the Magpul dvd's for the carbine and pistol but its definitely no substitute to actually going out and getting the trigger time. That being said my brother and I plan on making a range trip once a week from now on.
50 yd zero for me. There's also a lot of good info in this thread with excellent graphs from Molon (look on page 3)
https://www.m4carbine.net/showthread.php?t=37069
There's one more zero thread that I can't track down right now
What would be the best way to setup a M4 for a 50 yard zero? Can't seem to find any laser boresight targets for 50 yards for red-dots/eotechs
remove the upper and the bcg from the upper. secure the upper in a solid rest. look through the bore at something at 50 yds. bring the sight into alignment with that. confirm by actually firing the gun...
StraightShooter7
10-01-10, 11:42
+1 to the 50 yard zero! I just sighted my new Aimpoint M4S in at 50 yards and was very pleased with the results. I sighted in using the bench of course but once I got it zeroed I started shooting while standing. Lets just say that I need more practice shooting off-hand like that. I've been watching the Magpul dvd's for the carbine and pistol but its definitely no substitute to actually going out and getting the trigger time. That being said my brother and I plan on making a range trip once a week from now on.
This is exactly right. IMO, way too many people spend all their time shooting their home defense/SHTF ARs from the bench. A while back it dawned on me that if I ever had to use an AR for defensive purposes it is almost guaranteed not to be from a comfortable bench. This is why I try to spend at least half the time shooting my AR’s standing.
barrelwrench
10-01-10, 11:57
:lazy2:I do the old school zero as ra2bach mentioned. Most shooters in this area want a 100 yard zero. So my zero is a little different but the mechanics are just about the same. I use a 1 1/2 blaze orange paste at 100 yard and refer scope to barrel picture. I have a periscope that fits in the chamber for my aging eyes. I would also say that zero is more or less mission/shooter specific and you can't say that one is better then the other. I'm old Corps, and now my shooting days are more of metal and paper targets so I use the old 300 yard zero(scopes and irons, red dot is at 100). But I'm sure it's not what a LEO or CQB guy would want to use.
To each his own and what gets the job done.
Stay safe gents.
Failure2Stop
10-01-10, 17:25
I have used 300 yard zeroes (BZOs), 50 yard zeroes, 200 yard zeroes, 100 yard zeroes, and all the above in meters as well.
For shooting out to 200 meters, I have found the 100 yard/meter zero to be the easiest to deal with as far as hold-overs go if using an optic. You don't have to deal with any hold-unders for the entire trajectory, it is twice as forgiving at close range as far as hold-over goes, has the longest portion of POA/POI, and that POA/POI is at the most relevant threat distance where POA/POI most benefits the shooter. Further, most magnified optics with a BDC or range-relevent elevation adjustments are zeroed at 100, therefore there is more inherent crossover skill when changing between optics/guns.
A lot of shooters drastically overestimate their effective engagement range with M4 type weapons, or assume that if most threats will be inside 25 yards that a 25 yard zero will make the most sense. Both errors cause the shooter to have to deal with more things to compute when bullets need to find their mark. It's a lot easier to do on a flat range with clearly marked firing lines and distances with mental prep time and low stress. It is a much different problem when in the middle of a gunfight. Weighing zero against zero, and simply numbering pro's against con's does not give sufficient weight to the most pressing and life-threatening aspects. If you can have targets appear at unknown distances between 3 and 100 meters and be able to apply your hold-off to achieve a hit on the CNS without hesitation (and be correct), you and your zero are in harmony. If you can't, or if your hold-offs are tied to numerical distances in your memory, you are not. What it boils down to (to me) is that achieving that harmony is easier with a 100 meter zero than any other.
barrelwrench
10-02-10, 13:45
Agree with the harmony bit. Like I said, to each his own. Now let's throw some real world stuff into the mix (I'm not bagging on you Failure2stop so don't flame me) More of a survey, if you would.
1. Your on ACB, flag goes up and your leaving in 24 hours, your convention infantry. Iron sights. What BZO would you use?
2. Your a military designated shooter, scope, mill dots. 5.56 or 7.62, you choose. Urban and woodlands BZO?
3. Your a HRST/ SWAT team member with a AIM POINT. BZO?
4. Your a hunter in Maine, scope with standard crosshair reticle, 30-06
BZO?
5. Your a hunter in Montana, scope, standard crosshair reticle, 338 Federal. BZO?
Failure2Stop
10-02-10, 19:17
First, let's clarify some definitions.
BZO: Battlesight Zero. This is a sight setting that permits a shooter in full combat gear to hit a man sized target (roughly top of head to knees) from 0 to 300 meters (without accounting for weather effect) while applying a center-mass point of aim. This is pretty much a 300 meter zero, though many will zero at 300 yards out of convenience.
Zero: Achieving point of aim/point of impact at a specific distance. Purists will say that a Zero includes environmental effect, and that a "True Zero" is the same POA/POI without weather effect accounted for in the optic/sight adjustment. Further, one can Zero at a specific distance but with an impact point other than point of aim in an effort to more closely mirror a different distance's trajectory, but that does not change the fact that the distance involved is not the distance at which one expects to see POA/POI. If you don't put bullets into paper at that distance, you aren't really Zeroed at that distance, regardless of what the Google Machine tells you.
Anyway, to answer barrelwrench's questions:
100 meter zero to all.
Caveats:
1- There is no conventional US infantry that exclusively uses iron sights. When we used to use them, we used a rough 200 yard zero that was achieved by first zeroing the small aperture at 300 set on 8/3 or 6/3 (small gap), then flipping up the large aperture and confirming POI at 50 meters/yards. It was a sub-optimal approach.
2- Magnified optics: I will not use a long-range optic without finger-adjustable windage and elevation, and I have solid data so that I can determine range and environmental effect and dial it onto my optic to permit POA/POI out to my effective range or apply mildot-holds to achieve rapid hits. If you have a fixed/tool adjustable adjustments you severely limit yourself and your weapon's caipability at distances past max point blank range, which changes drastically based on cartridge and target size. I am not a subject matter expert on hunting elk/deer/prarie dogs/gophers/etc., so I defer to those that are, but when it comes to human threats, I know what I prefer.
BZO: Battlesight Zero. This is a sight setting that permits a shooter in full combat gear to hit a man sized target (roughly top of head to knees) from 0 to 300 meters (without accounting for weather effect) while applying a center-mass point of aim. This is pretty much a 300 meter zero, though many will zero at 300 yards out of convenience.
For those of us that come from the armored realm (tanks, LAVs, Brads, etc), recall the "B" for "battlesight." In the LAR community, BZO or battlesight doesn't refer to a "zero," per se, but a specific range as attributed to a specific ammo at which one could put a specific pip of the reticle on an adversary vehicle and be able to anticipate some sort of strike, be it a catastrophic kill, a mobility kill, an annoyance, or something off of which you could note impacts and shift to achieve one of the previous three.
In this case, if I went through the specified procedure to attain a 1000m zero, I could hold the battlesight of the reticle at 6 o'clock of mass and expect hits from 0-1450m with APDS-T or 0-950m holding center-mass with HEI-T. See, the "zero" is the same, but the battlesight range varies; it's a general term, one of employment. Maybe call it more of a goal...?
Hunters, you may be more familiar with ballistic references to "point-blank range," which as I understand it, tells you that given X zero and Y desired impact zone (like, 3" on a groundhog), you can anticipate hits within that specified zone from 0-???? yards (ick!)/meters/furlongs/parsecs, or whatever increment your fevered brain decides is applicable to your desired endstate (a dead critter, I'm guessing). Guess what, guys, if you've been cognizant of your point-blank range, you've been employing a BZO.
BZO/point-blank range, by definition, will allow you to attain hits on a specified size of strike zone BEYOND your actual zero range. It's a performance envelope, but the term is mis-applied in regard to describing POA/POI at a given range/ammo/barrel/human sacrifice combo.
barrelwrench
10-02-10, 21:34
I can say that I agree with some of what you both had stated about BZO. Santoro's statement is more to my thinking on PBR and BZO.
I do have to point out to Failure2stop that the Marine Corps still teaches iron sight in boot camp and OCS. It maybe a world of optics now a days but it don't make iron sight any less important.
Thank you both for your input and good info.
.
In a similar Thread, a few weeks ago, Molon brought up the terms – “Near Zero” and “Far Zero”. I hope this doesn’t add confusion.
If you sight-in at 50-yards, the bullet should cross the line of sight (LOS) at 50-yards (Near Zero) and again about plus/minus 220 yards. BUT you only have a “Near Zero” at this point. The “Far Zero” is just a guestimate until you actually shoot that guestimated range to verify it.
If you sight-in at 25-yards, the bullet crosses the LOS at 25-yards and then again around 400+ yards. Again, at this point, you only have a Near Zero.
The only sight-in range that doesn’t have a “Near Zero” and a “Far Zero” is a 100-yard sight-in because the bullet reaches the LOS right at 100-yards and does not go above the LOS. So, at 100-yards, the bullet grazes the LOS and then starts going to the dirt.
To have a “Far Zero” you need to shoot at that distant range to verify that the bullet does in fact cross the LOS again at that particular range.
Now, it has always been my understanding that the BZO (Battlesight Zero) is for doing a quick check of the sight when there is not time or distance to do a proper sight-in. That would fit F2S’s definition of being able to hit “top of the head to the knees”. Is this correct?
Now...does this make sense...?
.
No, that's more of a fringe benefit of a near-zero.
You can use it as a first step to get your zero by ensuring that you're on paper at distance, and you can use it as a means kinda-sorta confirmation of a KD zero already established, so long as you know where it's supposed to print in relation to a like POA as your KD zero.
Ergo, if you have a 50/200 zero that you've already confirmed @ 200, but you only have a 25yd range to work with and know that your rounds should print about something like 1.25" low at that distance with a center-mass hold, you have a pretty good idea that your zero hasn't changed.
killswitch1982
10-03-10, 04:47
Looks like I'll be doing a 50yd zero for my rifles from now on. Thanks for the info!
Failure2Stop
10-03-10, 11:51
I do have to point out to Failure2stop that the Marine Corps still teaches iron sight in boot camp and OCS.
Heh, I am well aware of what the USMC teaches to whom, and how and why they are evaluated in the manner that they are.
Don't be suprised when evaluating irons for entry level training is no longer the case. Nobody deploys with just irons on their rifles/carbines, so it doesn't make much sense to continue to teach irons when optics are what we do work with.
RE- Near Zero and Far Zero.
I have always used the terms "Initial Point" and "Zero Range" to describe the distances at which one achieves POA/POI, since the IP will vary depending on optic height, ammo, muzzle velocity, etc, as well as the fact that just because your ballisitc calculator tells you that if you are 1.5" low at 25 you will be dead on at 100 doesn't mean that when you actually zero at 100 the reverse will be true. For example; my work M4, when zeroed dead-nuts at 100 meters prints about 1" high and 1/2" left from the supposed POI at 25.
Now, it has always been my understanding that the BZO (Battlesight Zero) is for doing a quick check of the sight when there is not time or distance to do a proper sight-in. That would fit F2S’s definition of being able to hit “top of the head to the knees”. Is this correct?
No. It is a shortcut that grew into common practice within organizations. The 36 yard/33 meter zero is a Field Expedient BZO, and is intended to get the shooter on the frame at 300. At some point every zeroing exercise started to be referred to as "BZO" within the Corps, and there is a concerted effort by some to get that incorrect definition corrected in the minds of leaders. There is nothing about "Battle" or "Combat" prep that should be expedient or short-cutted. It's one thing to do a field-expedient fix to meet an immediate need, and an entirely different thing to accept that field-expodient fix as acceptable when the option exists to do something the right way, at least when lives are on the line.
barrelwrench
10-03-10, 20:24
That maybe in the far future but for now, and being a hot topic at this time in the MC, iron sights will be taught at entry level. I can only say until they have a near impossible to destroy optic or laser tracking small arms are standard issue...don't put those irons away. BUIS are popular for a reason. It's like saying you don't need to teach map & compass because we are so GPS dependent.
Back to my original post: what would you zero at with.... Zero is like a base line and I was curious to what people would zero at being that you just took it out of the box. Still no answer from any of the CQB guys.
Failure2Stop
10-04-10, 12:19
Still no answer from any of the CQB guys.
I answered above.
100 meter zero is the easiest zero for 3 to 200 meters(+/- depending on ammo).
And as far as optics and irons go, if you want to discuss it further, feel free to start a thread, but comparing modern optics and irons to compasses and GPSs is oversimplistic rhetoric.
As I add to most threads on zero...
The other variable to consider in choosing a zero distance is the proficiency of the shooter. At what distance is the shooter capable of sufficient accuracy and consistency to accurately reflect where the gun is dialed in to?
In addition to it's trajectory, one of the reasons that the 50yd zero is so popular is that it is a distance at which many can still perform.
All this is especially important for those responsible for those other than themselves.
Rmplstlskn
10-04-10, 16:46
The other variable to consider in choosing a zero distance is the proficiency of the shooter. At what distance is the shooter capable of sufficient accuracy and consistency to accurately reflect where the gun is dialed in to?
One of the primary reasons I do a 50yd... My eyes cannot see a 100yd target sufficiently to zero in a reddot without magnification... Minute of man, sure, but to zero, no...
Rmpl
I like JSantoro's approach: figure out what your vertical kill zone is and what your desired maximum point blank range is, and go from there.
50 meters works for me with an Aimpoint, but I'd be fine with 100 too. It would just mean using different holds at other ranges. This is where training matters. Know your holds and/or come-ups as appropriate for your optic.
I also like having a dependable iron sight that will support whatever range you want, in the field, repeatably. Either a cut down A2 rear sight or something like the KAC 200-600 m flip-up. You can do an improved BZO with a KAC flip-up and have repeatable settings for everything from 25 meters out to whatever, same as with a standard A2. Yeah I know... combat is not the same as Camp Perry, but if your rear sight supports multiple ranges without becoming a liability, I say go ahead and use it. It's infinitely better than fussing with a front sight tool or guessing holdover through a fixed rear sight.
The other variable to consider in choosing a zero distance is the proficiency of the shooter. At what distance is the shooter capable of sufficient accuracy and consistency to accurately reflect where the gun is dialed in to?
I think this, more than anything else, is the reason for the popularity of the 50 yard zero. If you told these same people that a 25 yard was a viable alternative, or a 7 yard, they'd zero there. :sarcastic:
RogerinTPA
10-04-10, 21:57
One of the primary reasons I do a 50yd... My eyes cannot see a 100yd target sufficiently to zero in a reddot without magnification... Minute of man, sure, but to zero, no...
Rmpl
Good point. Physical limitations should be factored in when adapting to the situation, gear or methods used to effect a desirable outcome.
Rmplstlskn
10-05-10, 07:20
I think this, more than anything else, is the reason for the popularity of the 50 yard zero. If you told these same people that a 25 yard was a viable alternative, or a 7 yard, they'd zero there. :sarcastic:
A bit pessimistic of your fellow carbine shooters today, heh? ;)
Rmpl
50 yd zero for me. There's also a lot of good info in this thread with excellent graphs from Molon (look on page 3)
https://www.m4carbine.net/showthread.php?t=37069
There's one more zero thread that I can't track down right now
I found an excellent ballistics tool and education by running a ballistics program. I use iSnipe app for the iPad/iPhone/iPod. You can put in all the variables, it will generate a comprehensive table at intervals and distances of your choosing, and draw the graphs for you.
barrelwrench
10-05-10, 09:40
He only had one cup of coffee today and the 7 yard thingie real gets to him.....said with humor.
I see SWAT magazine had a decent article on off set and zero. I may change my ways. Who said you can't teach an old gunny new tricks.
A bit pessimistic of your fellow carbine shooters today, heh? l
Shooters? No. Owners? Yes.
Shooters? No. Owners? Yes.
An important distinction.
Add those whose carry of them is compulsory to the list as well.
barrelwrench
10-05-10, 10:45
Come on guys' there are no posers or wannabes on this site.:D
Elmer Fudd
10-05-10, 13:35
Paul Howe at CSAT has a good article on zeroes. He does not like the 50/200 yard (which is what I use, as much for the fact that my civilian AO does not have many 200 yd+ lines of sight):
http://www.combatshootingandtactics.com/published/thebattlefieldzerofullpictures.pdf
He has some other articles which might interest folks here:
http://www.combatshootingandtactics.com/published.htm
jsbsmarine
10-05-10, 16:54
Any suggestions for a 10.5in LMT barrel zero? Using a simple aimpoint M2 on it.
Thanks
Who said you can't teach an old gunny new tricks.
Heh, it can be done, but one may pay a price. It can be a Phyrric victory
Just suggesting something as simple as a 100m co-alignment of a Marine's PEQ laser with the RCO chevron (instead of the idiotic 300m zero in the TM) has, for me, sometimes resulted in a scene that looked like this:
http://img408.imageshack.us/img408/3351/frankensteinvillagers.jpg
BUISs are becoming more and more common in the Corps, now. Suggesting ANY zero other than the "book" zero, the reaction (think sodium + water) can sometimes make somebody outside the conversation think I'd just wiped my bum with the national ensign. :D
The 100 works. The 50/200 works. One can use an Analogue Decision Generator (AKA, "coin") to choose between the two and make the result work, though it helps to futz with both, circumstances permitting.
barrelwrench
10-05-10, 22:07
Hey. That looks like the last wet down I attended. You got a guy by the name of fooley working with you at Q.:laugh:
The only sight-in range that doesn’t have a “Near Zero” and a “Far Zero” is a 100-yard sight-in because the bullet reaches the LOS right at 100-yards and does not go above the LOS. So, at 100-yards, the bullet grazes the LOS and then starts going to the dirt.
even after having been a shooter for many years, I found this concept fascinating.
talking about the common 5.56 carbine, I know that the height the optic is mounted above boreline is a component in this but is there something magical about 100yds.? is there any other distance, possibly further, that this occurs?
I always understood and accepted the concept of "point blank range" in that the POI will never deviate more than X inches from POA over a certain distance. for instance, an 8" kill zone indicates that the bullet never rises, nor drops, more than 4" from the POA. this works well for hunting where animals have an X inch size kill zone. faster, hence "flatter" shooting, cartridges increase this range, as does a larger kill zone.
and I readily understand that this involves the POI being either under or over the POA depending on which side of your zero the target is and either holdover or hold under is required. but it simply never occurred to me that there was a distance at which the POI rose to the POA but did not rise above it.
the fact that with this zero, there are only holdovers is a revelation. it caused an epiphany in me. I don't know why I didn't realize this before! :eek: this certainly changes how I'm going to think about things from now on...
I made a comment on another Thread that if the bullet crosses the LOS at 50 yds for a 200 (or so) Zero, that I didn't think the front post would have enough adjustment to do a Zero at a 100 yds. I thought the bullet would have to cross the LOS around 10-15 yds to be able to drop back down to Zero at a 100 yds.
I was figuring the traj would be about like a slow pitched softball. (Did my "incorrect" thinking make sense)
Well, the Honorable MOLON was quick to graciously correct me. He's the one that explained the traj to me like I stated in my previous post.
LOS is LOS, so I wouldn't think it would matter to an AR if it was RDS or Open Sights, the trajectory would be the same. The height the LOS is above the bore, bullet speed, and weight pretty much dictate this 100-yard traj.
To me, with my T-1, I like the 50/200 yds sight-in. I know that the traj out to 250 yds or so will be covered by (or just inside) the Red Dot.
Thanks!
When putting on a new sight or scope, I seperate the upper and remove the BCG... I then peek through the barrel at some object and while holding the upper still I adjust the sight/scope to that object. Then you move to the 25yd paper... Really easy, honest...
Rmpl
+1 to this.
Boresights are a huge waste of money, this works every time with any rifle assuming you have a good rest or just some decent shooting bags...
+1 to this.
Boresights are a huge waste of money, this works every time with any rifle assuming you have a good rest or just some decent shooting bags...
...and the gun has a design that will allow you to look straight through the barrel. (Won't work on most auto, pump, lever guns + others)
They're a waste of money if you're worried about the crown on a precision gun, as one rightly should be. Even then, there's chambered laser boresighters, which generally obviate the need to collimate anything, as there's loads of both optical and laser boresighters that require that for best results.
They're also a waste when one can't be bothered to learn how to collimate the ones that need it, which is a bigger trend than those that know what that means, much less do it. The military LBS/PEM-1 and similar systems is just one example of a market full of them.
No different than conducting a near-zero grouping exercise. Seen as a means of preventing waste of time and ammo on the line, they're often a smart choice if you don't want to have to break a gun down, have problems seeing a target through a barrel or a reticle pattern on an optical model, etc. Seen as an alternate to shooting for groups to determine or confirm zero...yeah, all kinds of waste going on there.
In and of themselves, boresighters can be an enormous help, which in no way advocates that everybody should be using them. You have a whole golf-bag of clubs to get your ball on the green, how you choose them is on you (or your caddy...man, what a shitty analogy THAT is).
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FYI
Today Molon started a new thread expounding on the 100-yard as well as other zeros... AR-15 Zeroes and Trajectories (https://www.m4carbine.net/showthread.php?p=798060#post798060)
Typical Molon 1st class quality.
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I set mine at 200 yds and shoot apples at that range,good enough for me. Ammo Hornady 75gr bthp match, they recommend the 200 yd zero..:happy:
DirectAction
10-30-10, 05:33
Mine are set up for 50 yards.....used for my profession, it is the most practical.
Great references and opinions guys.....
Thanks!
The agency that I work for now has our carbines zeroed at 100 yds. How or who decided this was optimal for our function I don't know, but I am glad to read comments from experienced folks saying it is good up to 300 with the least holdover.
I'd be interested to know from guys who are LE here what their agencies prescribe as their zeroes. Outside of active military with combat arms roles, I would venture to say that we'd be the closest runner up for relevance and importance in the matter. I am also not talking about any SWAT or tactical teams, rather patrolmen, line agents, etc.
Oddly enough, I use a 50 yd zero on my personal carbine despite military experience (USMC zero), and current agency standards (100 yd zero). I figure for HD, it would be optimal...
Just wanting some verification as to if I figured this out correctly...
I was running a 50 yd BZO and re zeroed it to a 25 a couple of weeks ago to experiment on some longer range targets. I didn't note my "click changes" (thinking about bringing a notebook from now on) then.
Im going to the range in the AM and plan on changing my zero from 25 yd to back to 50 yd.
In the past I would just shoot a group and adjust, but now Im thinking that if I do the math correctly I could just dial the dot down the right distance and that should put me closer to the 50 yd BZO neighborhood to start out with.
With an EoTech that has 1/2 MOA adjustments Im figuring that if I dial the dot DOWN 10 clicks (1' 1/4") from my 25 yrd BZO that should put me back close to the original 50 yd BZO.
Right?
dont need a boresighter.
+1
They are a waste of time and money unless you are firing expensive magnum hunting cartridges or African dangerous game rounds and can't afford to waste ammunition.
I am not a subject matter expert on hunting elk/deer/prarie dogs/gophers/etc., so I defer to those that are, but when it comes to human threats, I know what I prefer.
Every magnified optic I have bought in the last 10 years of my hunting career has finger adjustable adjustments.
Adjustments with screwdrivers/coins are a thing of the past.
On a side note, I also will no longer buy a scope with a 1" tube for any rifle for any reason. 30mm lets more light in and has more adjustment. People have a thing about thinking a 30mm tube is "European" and that is why they weren't popular in America until the last 10 years or so.
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