View Full Version : 25 yard range: zero?
SpookyPistolero
05-16-10, 21:00
Howdy folks-
I've abused the search function for a while but couldn't find a thread on this subject (I'm open to old info of course!).
There's a new indoor range opening near me that will allow me to get some good range time, but unfortunately the lanes are 25 yards. Does anyone know where to zero the rifle on a 25 yard target to get a good 50 or 100 yard hit? Or at what range the bullet would come back down when using a 25 yard zero?
As the primary role of the rifle is defensive use, I'm not too terribly upset about having just 25 yards, but I'd like to know what I ought to hit at further ranges using that zero.
Thanks for any info-
the military has used a 25m zero since the early days of the m16... it's an OK zero. the round will zero at 25 and then again at 300, with a pretty good sized hold-under at intermediate distances. i used a 25m zero all the way up until about a year ago, before finally switching to a 50/200 z... it works, it's just unnecessarily complicated if you don't do a lot of 300m shooting.
Use this target - it has aiming points for both 50 and 100 yd zeros at 25 yards.
PDF file of target (http://www.lawofficer.com/Images/100yardzerotarget_tcm22-158738.pdf)
falightfighter
05-16-10, 21:12
FM 23-9, CH 5 discusses the ballistics of M855 and M193 in the M16A2. http://www.globalsecurity.org/military/library/policy/army/fm/3-22-9/index.html
Changing any of the variables (bullet weight and barrel length, primarily) will change the data, but will give you a starting point.
The wikipedia article (http://en.wikipedia.org/wiki/External_ballistics) has a chart that compares the M16A2 and M4 using M855 ammo.
I'm sure there are those more knowledgeable than I that can give you more data.
SpookyPistolero
05-16-10, 21:15
You guys rock my face off, that was just the info I needed. (And in like 5 minutes flat :D )
ForTehNguyen
05-16-10, 21:23
50 yard zero is the best. If you dont have access to a 50, you can zero 1.2 inches low at 25 yards, which will be dead on at 50. This chart is for a 14.5" barrel but Im gonna guess that its not gonna be that much different at these ranges for a 16"
http://www.jesseshunting.com/photopost/data/500/medium/Zerobulletpaths.jpg
http://img263.imageshack.us/img263/9287/batsignal.jpg
We need a "Molon signal" like the above.
Take a look at his and others' ideas, thoughts, concepts and proof here: https://www.m4carbine.net/showthread.php?t=34671
Alternatively, you can use the standard military zeroing target (with the little black tombstone like silhouette) that's made for 25/300 zeroing.
Be sure to use the correct M16 or M4 version.
Roll it out to 25 yards. Group it nicely into the target until satisfied. You now have a 25/300 zero. Now adjust your front sight "down" (as in the round strike) 2 clicks. Now you have a 50/200 zero which is much more useful. Thus said my last carbine class.
Can't say that I'm sure what that translates into if you're adjusting an optic though... :D
Zero for POI about -1.2" below POA at 25yds for an approximate 50yd zero and all the benefits thereof.
I like the PDT/David Blinder target for this purpose.
http://www.personaldefensetraining.com/showpage.php?target=zerotarget.php
The one from LOKNLOD is a good one, too.
SpookyPistolero
05-16-10, 22:12
More good info and links guys, thanks much. Bookmarked!
RogerinTPA
05-16-10, 22:43
I also use the 50/200 yard zero on my ARs.
I zero at 50 yds for all my rifles
1.5in. low at 25 for a 100yard zero. Taught in my armorers course and in OPOTA (Ohio Peace Officer) Rifle classes.
printable target http://lawofficer.com/Images/100yardzerotarget_tcm22-158738.pdf
Article for thought http://lawofficer.com/news-and-articles/articles/lom/0402/long_gun_zero.html
Both of my ballistic calculators say 1.2" below POA @ 25, based on a 2.5" height-over-bore with a carbine-length barrel. This coincides with ForTehNguyen's chart; say, 30.5mm. Calling it 1 1/4" makes it easier to measure if you don't have a decimal-based ruler and are happy with "close enough." I don't think .05" of difference would be a statistically significant difference.
It needs to be re-iterated: these close-in or offset zeros are field-expedient methods, and still require confirmation at known distance for the shooter to be absolutely sure where they'll print, if for no other reason than to account for unknowns: differing barrel lengths, ammunition, sight height, etc. etc.
For example, my own calculator shows my 50yd zero (for my rifle and the ammo I usually shoot) to re-cross LOS @ 205m, pretty much exactly where I want it (nobody fights in yards, any more). This has been confirmed by shooting the piss out of it, but not everybody has the space to do this, so it all depends on your personal level of OCD. :p
I guess I am odd but I like to zero at 300 yds (after getting on the paper at a closer range). For long range rifles, I stick with a 300 yd zero. For intermediate rifles I will set it 4 to 6 inches low at 300 yds, as I do not want the bullet 10 in. above point of impact. When I say zero at 300 yds, that means the target is at 300 yds. Small errors at 25 yds are magnified by a factor of 8 at 300 yards, so a more precise zero is obtained by zeroing at the longer distance.
It needs to be re-iterated: these close-in or offset zeros are field-expedient methods, and still require confirmation at known distance for the shooter to be absolutely sure where they'll print, if for no other reason than to account for unknowns: differing barrel lengths, ammunition, sight height, etc. etc.
The above is critical. Cant be repeated enough.
For example: I run a Trijicon TR24G in a 1.93" height LaRue mount which places the tip of the triangle (Line-of-Sight) approximately 3.15" above my Line-of-Bore. The typical Line-of-Bore/Line-of-Sight "Off-set" differential with iron sights is 2.5". I need to account for that differential when zeroing my optic vs. my irons.
I also need to account for that extended differential when shooting at closer (Less than 15yds) distances with my optic. Instead of 2.5" hold-over with my irons, I need to use a 3.00"+ hold-over at 15yds and closer.
I prefer a 100yd (Point-of-Aim/Point-of-Impact) zero because its trajectory is flatter throughout the ranges I am likely to encounter on-duty (0-150yds).
YOU need to figure out at what distances YOU are likely to make engagements at with your rifle before YOU decide on which zero is "best" for YOU.
If you dont see yourself needing to take a shot with your rifle beyond 125-150yds, then a 100yd zero will suit you well. Although shots out to 300yds using a 100yd zero are simple as long as you know your hold-overs.
If you see yourself needing to take most or many of your shots out past 200yds, then a 50/200yd zero suits you better in my opinion.
Failure2Stop
05-17-10, 05:25
It needs to be re-iterated: these close-in or offset zeros are field-expedient methods, and still require confirmation at known distance for the shooter to be absolutely sure where they'll print, if for no other reason than to account for unknowns: differing barrel lengths, ammunition, sight height, etc. etc.
Absolutely.
FWIW- in my experience with zeroing large groups of people using TA31s on M16A4s and M4s at 25 and 100 meters with M855 there is a significant difference in 25 meter zeroes and strike of round at longer ranges.
The difference between 20" barrels and 14.5" barrels is pretty significant at 100 meters if both are initially zeroed at 25. We use 25 meters only to get hits on paper before moving back to 100.
Since most of our shooters are using TA31s the 25m POA/POI is with the tip of the vertical post (300m) and at 100 POA/POI is at the tip of the chevron.
As I said before, I have never seen anyone achieve a satisfactory zero confirmation at 100 meters without adjustment following the 25m zero with an M4, and 20" barrels are nearly always high by 2 to 3 inches.
That might be ok for a casual shooter, but not for me.
variablebinary
05-17-10, 06:23
25 meter zero works well for me.
Zeroing at actual distances of 200/250/300 is great if the shooter is of sufficient ability to get a true and reliable zero. Most are not.
Having shooters zero at closer ranges and then verify/fine tune at distance is a more reasonable expectation. Some will still struggle with real distances even for gross verification, and may be better off leaving their sights alone, especially if their likely engagements are at those closer ranges. The difference between the 100yd and 50/~205yd zeros at 25yds is -1.5" POA and -1.2" respectively. Three tenths of an inch, or slightly more than the diameter of the round the shooter is firing. If they can't produce that .3" difference on demand at 25, what's the hope farther out?
Yeah, cogent point. The primary thrust of the field-expedient methods is to ensure that the shooter will, at the very least, print on the target at KD so that groups can be plotted and adjusted to desired POI. Nuts, even at 25m or thereabouts...
Among my own "customers," if I see a significant percentage of a given group that are printing groups @ 33m with the RCO that I can't cover with a quarter...minimum!...I automatically pregame and double-down my aspirin intake for the icepick-in-right-eye headache I just know is coming down the pike, since that means the 100m confirmation is gonna be a Sisyphean task.
Like getting beaten to death with feathers...
interestingly the .mil is getting the message re the 50 yd zero being best. When at train up to go to Afghanistan in 08 they made us zero at 25(the vast majority of mil ranges are set up for 25) but adjusted our sights to keep the shot group in the lower 1/3 of the target at 25.
1911sforever
05-17-10, 12:35
Very interesting thread. It's good to see that the .mil is belatedly recognizing the difference in the average engagement ranges between Iraq and Afghanistan.
Failure2Stop
05-17-10, 12:37
Very interesting thread. It's good to see that the .mil is belatedly recognizing the difference in the average engagement ranges between Iraq and Afghanistan.
There is a big difference between what "Big Army" does, and smaller, more nimble units and switched on individuals/instructors.
SpookyPistolero
05-17-10, 14:00
Thanks again for the info guys, and of course I'm not going to be making any assumptions about where my rifle will put around at 100 yards. I don't make assumptions when it comes to defensive stuff. Just want to have a good notion beforehand if I get to a longer range.
We were taught 25 meter zero is zero again at 250 meters and the round wil hit inside a 9 inch square anywhere in between those 2 ranges.....1968 US Army training..
We were taught 25 meter zero is zero again at 250 meters and the round wil hit inside a 9 inch square anywhere in between those 2 ranges.....1968 US Army training..
My issue with a 25m zero is exactly that. Most of the 9" of elevation hold-over occurs within the distances I am most likely to need to make engagements (0-150yds). With a 100yd zero (aside from the usual 0-15yd, 2.5" Line-of-Bore/Line-of-Sight off-set), I only need to take less than an inch of elevation in to account.
Makes sense to me. I have a DCM that is sighted in exactly as you describe. Works for me...
RogerinTPA
05-17-10, 19:39
We were taught 25 meter zero is zero again at 250 meters and the round wil hit inside a 9 inch square anywhere in between those 2 ranges.....1968 US Army training..
So was I, but we have to understand that zero is based on the lowest non switched on, common denominator. Maybe 10% of any platoon, had a hunting or competitive shooting background with high powered weapons. Most 11Bs I came across, were not skilled shooters, by any stretch. Once a year quals, don't cut it. current 2-4 times a year, still doesn't cut it. Holder overs, by and large, is an alien concept, across the board (X 10 if in any other Army branch other than SOF units).
Howdy folks-
I've abused the search function for a while but couldn't find a thread on this subject (I'm open to old info of course!).
There's a new indoor range opening near me that will allow me to get some good range time, but unfortunately the lanes are 25 yards. Does anyone know where to zero the rifle on a 25 yard target to get a good 50 or 100 yard hit? Or at what range the bullet would come back down when using a 25 yard zero?
As the primary role of the rifle is defensive use, I'm not too terribly upset about having just 25 yards, but I'd like to know what I ought to hit at further ranges using that zero.
Thanks for any info-
For the sake of simplicity and clarity of discussion, the points in this post will be based on an M16A2 firing M855. For starters, US Army doctrine for zeroing an M16A2 does not call for a 25 meter zero and a 25 meter near-zero will not produce a 300 meter far-zero. The US Army doctrine calls for a 300 meter zero, which is obtained at a field expedient distance of 25 meters, with the rear sight elevation drum adjusted one click above the 8/3 setting during the zeroing process and returned to the 8/3 setting when the zeroing process at 25 meters is complete.
Lest you think I’m arguing semantics, view the trajectory graphs below. A 25 meter near-zero will produce a 350 meter (388 yards) far-zero.
http://www.box.net/shared/static/f2aede6t0d.jpg
A 25 yard near-zero will produce a 411 yard (374 meters) far-zero.
http://www.box.net/shared/static/cednvi8d7o.jpg
The 300 meter zero called for by US Army doctrine produces a near-zero of approximately 30 meters or approximately 33 yards.
http://www.box.net/shared/static/yleso2f74i.jpg
Now, to answer your question. To obtain a 50 yard zero, at the field expedient distance of 25 yards, adjust your sights so that your point of impact at 25 yards is approximately 1.2” below your point of aim. The far-zero will be approximately 234 yards.
http://www.box.net/shared/static/zhhh274yna.jpg
For additional information on the subject, see my posts in the following thread:
https://www.m4carbine.net/showthread.php?t=35064&highlight=ribz
We were taught 25 meter zero is zero again at 250 meters and the round wil hit inside a 9 inch square anywhere in between those 2 ranges.....1968 US Army training..
Since you reference the year “1968,” I’ll assume that you are referring to the M16/M16A1 sights; in which case your statement above is incorrect. The US Army doctrine for zeroing the M16A1 calls for zeroing the rifle at the field expedient distance of 25 meters, using the long range aperture; “L”. According to the FM 23-9, this produces a near-zero of 25 meters and a far zero of 375 meters, not 250 meters. After the zeroing process is completed, the A1 rear sight leaf can be flipped to the "short-range aperture", which according to the FM creates a 250 meter far-zero, with a 42 meter near-zero (approximately 1 inch low at 25 meters). Neither condition produces a 25 meter/250 meter zero.
http://www.box.net/shared/static/my6r5u0ygi.jpg
It's not a confirmed zero until you've shot it at the range you intend to hit -- period.
Everything else is an off-set or guess.
It's not a confirmed zero until you've shot it at the range you intend to hit -- period.
Everything else is an off-set or guess.
Yeah, I remember my mild surprise at the fact that I had to do a bit more work to get my carbine zeroed at 100 yards after "very precisely zeroing" at the prescribed -1.6" inches at 25 yards (I was going for a 100 yard zero). So if you are zeroing at 50/200, if you expect to actually hit something at 200, you better zero at 200. This is another reason I like to zero at 100 yards, because it is easier to find a 100 yard range than a 200 yard range, and it gives a very flat trajectory all the way out to 200 or 250 yards (you'll only be roughly 1.5 inches low at 200, and 4 inches low at 250 yards).
And besides, Paul Howe likes the 100 yard zero the best, so if it is good enough for him, I figure I'll take it :D
Hello all. I just got my first AR. It is a Colt LE6940. I just has a few questions on zeroing the sights.
First of all, what tool do you recommend to adjust the front sight? I am familiar with adjustment of my AK front sight, and was wondering if this AR needs a tool? I know the front sight is a bit different from the standard as it is a flip up, but I think the adjustment should be the same, no?
Next, I plan at zeroing at 50/200 yards. With the Matech BUIS, what do I set the elevation dial to? I have heard 200m, 300m, and even the line after the 300m? This rear sight seems a bit different from the standard as it only has one flip up aperture, and does not have a 8/3 setting. Here is a picture http://www.triggeraction.com/TA/images/MATBUIS_1.jpg .
Thanks so much guys for helping out this newb.
Hello all. I just got my first AR. It is a Colt LE6940. I just has a few questions on zeroing the sights. First of all, what tool do you recommend to adjust the front sight? I am familiar with adjustment of my AK front sight, and was wondering if this AR needs a tool? I know the front sight is a bit different from the standard as it is a flip up, but I think the adjustment should be the same, no?
Bullet tip, ball point pen, punch, or front sight tool.
Next, I plan at zeroing at 50/200 yards. With the Matech BUIS, what do I set the elevation dial to? I have heard 200m, 300m, and even the line after the 300m? This rear sight seems a bit different from the standard as it only has one flip up aperture, and does not have a 8/3 setting.
Mine, zeroed at 50. I have no use for elevation adjustments and ignore them.
http://i76.photobucket.com/albums/j18/Skintop911/e0c1dbbc.jpg
I use a front sight tool on mine...should be easily available online from Brownells, MidwayUSA, etc.
Interestingly enough, the front sight tool that works on my conventional fixed front sight on one AR won't work on my flip-up Troy sight on the other AR. Something to keep in mind.
Also, good choice on a first AR. :cool:
Bullet tip, ball point pen, punch, or front sight tool.
Mine, zeroed at 50. I have no use for elevation adjustments and ignore them.
http://i76.photobucket.com/albums/j18/Skintop911/e0c1dbbc.jpg
Awesome just what I needed. So one more time to get this straight. If I want a 50/200 yard zero, I can zero at 25 by adjusting POI about 1.5 inches low, or I can zero directly at 50 with POI in center?
Sorry. I am a bit slow.
ForTehNguyen
05-24-10, 09:37
Awesome just what I needed. So one more time to get this straight. If I want a 50/200 yard zero, I can zero at 25 by adjusting POI about 1.5 inches low, or I can zero directly at 50 with POI in center?
Sorry. I am a bit slow.
well thats a ghetto zero for 50 if you dont have access to a 50. Its about 1.2 inches lower not 1.5 on a 25 yard target. Obviously the 50 yard zero dead center would be the best.
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.