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.
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.
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"
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…
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.
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.
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.
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.
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?
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