Advanced Site Zeroing Tricks

[Nephrology]

So thinking about different ammo and I’ve always been able to get by with M193 as a cheap substitute for practice, I decided to see just how close everything is.

Started off with my 16” Sionics pencil barreled gun with the Trijicon Accupower 1-4 with the segmented circle reticle. It’s zeroed for my hunting reloads consisting of a Nosler 55 grain ballistic tip at 3100 FPS with TAC. I put the dot on top of the top white label and fired 5 shots. Not really shooting for groups just shooting as soon as the dot came back on target. This was at 200 yards and I aimed high because it is zeroed at 100 yards.

Then I shot IMI M193 at the second label in the center not thinking about the 100 yard zero.

The third was my 77 grain MK262 clone again center of the label.

The fourth was my 62 grain MK 318 clone, I knew I pulled the low shot.

The only load that was really off is the MK 262 about 2” right. I thought maybe I had my head not centered or who knows what so I shot another 5 shots on a different target with the same results.


Everything was about 1.5 moa and that’s all I expect from this gun and my shooting. Not bad for a chrome lined pencil barrel at 200 yards with a 1-4 scope.

I've also noticed ammunition specific differences in windage @ 100M that always drives me crazy.

re: rifle zeroes in general, I zero all of my rifles at 100M because that's a distance that works for me as good mental benchmark and I can live with knowing the holds. That said I did just get my first Eotech, so on that rifle alone playing with a 50/200 for the first time. I don't think it really matters practically if you know your holds. This stuff really matters most when you are going very very precise shooting, consider that with 100M zero and 2MOA red dot my holds are about 2" at 10M, and again probably 2" at 200M. How much that shift matters for your envisioned application of a rifle may vary, but for my HD ARs I really do not worry about the zero at all.

[TWR]

I thought I zeroed this carbine at 100 because of the BDC reticle but have figured out that a slightly high zero at 100 is on at 200. I also shot it at 50 yards today and it was slightly low. (Slightly meaning top or bottom of bullseye) But it was centered with the MK 262. Just shows how close things can be and still be off. That’s why even with the 50/200 zero you must shoot it on at 200, 50 is just close, not a zero.

My carbine with an Aimpoint is sighted at 50/200.

I’ve focused on pistols so much lately that today’s short break with the carbine was fun. I might have to do it again.

[rob_s]

It’s been quite a long while since I spent a lot of time sorting out zeros etc. on carbines, so maybe some of this is dated.

First of all, if I have an optic that’s designed to work with specific zeros, then I’m going to zero at those distances.

Second, I would always zero using the “critical use” ammo of choice and then check the zero with the blasting ammo. I don’t recall ever seeing a difference large enough to matter for my use. I could easily make the argument the other direction though, since it’s the blasting ammo that’s getting shot the most. Either way, just be consistent with your approach and check it both ways.

Other than specific optics, I arrived at a 100 yard zero for my ARs as a standard. Main reason being that doing so meant I never had a hold under, only hold over. The image below has been circling for years, and these days with far more optic heights and ammo types and calibers and barrel lengths, it’s not a guarantee but it illustrates the basic concept, which is that you’re pretty much within 2 in out to 200-ish yards. Again, you need to verify at the range.

Finally, if possible, I prefer to zero the way I’m going to shoot. Which means that if my only time at a bench is going to be when I zero, then I’d prefer not to zero that way. Or, if I must, then I want to do some range checks and verifications in “field” conditions.

Chart mentioned above.

[UNM1136]

@Wake27 brought up a lot of excellent points.

I have dealt almost exclusively with 16.1 and 14.5 inch barrels for the last bunch of years. When someone shows up to a class with an SBR or a 20 inch barrel they will get some special attention shooting at 200 and 300 to make sure they understand what they are doing at distance. I like to put new rifle shooters on steel at 500 yards as a confidence builder and fundamentals test.

The 50/200 zero is a compromise. "Good enough" to have the POI be "roughly" within three inches of POA from contact to approximately 220 yards. This is, by definition, NOT a zero. This is a physics cheat to reduce amount of math and accomodation one has to do in a crisis. It is a 50 yard zero that you can use to be "close enough" at other distances. I am also rethinking the 100 yard zero. And LPVOs.

My biggest cheat: if my 2MOA dot covers ear to ear, I hold on the head to hit COM. I am just over 300 yards with about a 9 inch drop with my rifle and round. When I get my SUURG upper from Larue next year I will spend a lot of time and ammo figuring dope with a 50/200 or 100 yard zero.

pat

[frozentundra]

What are some advanced tricks and tips to zeroing carbine sights? Let’s not limit this to AR15s necessarily, but that’s what I’m mainly interested in.

This is pretty much the opposite of advanced, but I've found it helpful when zeroing scopes with vertical and horizontal reticle components to the fall of gravity.

I like to use a big ass piece of cardboard with two long strips of hi viz tape. Duct tape or blue painters tape work fine and most people have them laying around. Instant repair centers/pasters are a side benefit. Amazon orders supply the big ass cardboard fodder.

I apply a long vertical piece of tape, taking care to keep it straight. Then I set up the cardboard using a level to make sure the tape line is plumb to the fall of gravity. Next I use the level to mark a horizontal line. Next I apply the horizontal tape that is now level to the fall of gravity. This insures my scope is zeroed precisely to the fall of gravity by providing gigantic reference marks that keep my crosshairs level. Easy to see with low power scopes even at extended distances.

If you don't have a level, simply tape a piece of string to the top of the cardboard along one edge of the vertical tape. Tie or tape a weight to to the bottom of string for an integrated plumb-bob. A shoelace and a rock will even work in a pinch. You can live with having to rely mainly on the vertical reference.



I prefer to zero my carbines with a "maximum point blank" zero, which is something along the lines of the 50/200 scheme. This is mostly because of shooting pests like coyotes. They are moving targets of varying size at unknown distances. To me this simplifies fast shots in the zone between 200 and 275 yards, which seems to be an important hot zone for smacking coyotes around my property. My grandfather did this for his hunting guns and it just stuck with me. I suppose most people don't have this concern for their carbine usage in 2021.



With regard to different loads, I enjoy having optics with reset-able turrets. My SWFA ultralight 2.5-10 and my SWFA 1-4 both have the ability to set zero for a primary load and then dial to accommodate various other loads. I could wish the 1-4 reset-able turrets were capped like the 2.5-10, but it hasn't ever given me trouble in practice. I wish more LPVO had capped, reset-able turrets like the SWFA 2.5-10 design. It solves some problems.

[Sanch]

Question for the group:

It’s far easier for me to do a 25 yard zero than a 50 or 100 or 200 yard zero because the local indoor range is 25 yards and the outdoor range is much further away and more of a hassle.

Assuming I’m not in SEAL Team 6, but assuming I do want a 50 yard zero for carbines for LARPing, can I get away with a 25 yard zero and then some arbitrary number of elevation clicks to estimate a 50 yard zero? And if/when the opportunity arises, I do the actual zero at 50 or 200?

Each aimpoint click is 1/2” at 100 or 1/4” at 50

Supposing I’m zeroed at 25, I could probably look at a ballistic chart, see where it’s supposed to hit at 50, and then adjust the aimpoint elevation by as many clicks in the appropriate direction in 1/4” intervals.

Blasphemy, I’m sure, but the desire to have a 50/200 zero for TSHTF doesn’t outweigh the cost of actually traveling to an outdoor range to do it.

The more likely concern is hold overs for sub 25 yard distances, which I can do in my local indoor range. Since in the extremely unlikely event I’m going to use an AR for realsies, it’s going to be up close. So I’m thinking of 25 yard zero plus a few clicks TBD, then review holdover data.

Anyone else do something like this?

[rob_s]

Question for the group:

It’s far easier for me to do a 25 yard zero than a 50 or 100 or 200 yard zero because the local indoor range is 25 yards and the outdoor range is much further away and more of a hassle.

Assuming I’m not in SEAL Team 6, but assuming I do want a 50 yard zero for carbines for LARPing, can I get away with a 25 yard zero and then some arbitrary number of elevation clicks to estimate a 50 yard zero? And if/when the opportunity arises, I do the actual zero at 50 or 200?

Each aimpoint click is 1/2” at 100 or 1/4” at 50

Supposing I’m zeroed at 25, I could probably look at a ballistic chart, see where it’s supposed to hit at 50, and then adjust the aimpoint elevation by as many clicks in the appropriate direction in 1/4” intervals.

Blasphemy, I’m sure, but the desire to have a 50/200 zero for TSHTF doesn’t outweigh the cost of actually traveling to an outdoor range to do it.

The more likely concern is hold overs for sub 25 yard distances, which I can do in my local indoor range. Since in the extremely unlikely event I’m going to use an AR for realsies, it’s going to be up close. So I’m thinking of 25 yard zero plus a few clicks TBD, then review holdover data.

Anyone else do something like this?

Lots of people do.

A) doesn’t mean it’s right but…
B) most of them don’t actually shoot the gun anyway so it doesn’t matter!

[Wake27]

Question for the group:

It’s far easier for me to do a 25 yard zero than a 50 or 100 or 200 yard zero because the local indoor range is 25 yards and the outdoor range is much further away and more of a hassle.

Assuming I’m not in SEAL Team 6, but assuming I do want a 50 yard zero for carbines for LARPing, can I get away with a 25 yard zero and then some arbitrary number of elevation clicks to estimate a 50 yard zero? And if/when the opportunity arises, I do the actual zero at 50 or 200?

Each aimpoint click is 1/2” at 100 or 1/4” at 50

Supposing I’m zeroed at 25, I could probably look at a ballistic chart, see where it’s supposed to hit at 50, and then adjust the aimpoint elevation by as many clicks in the appropriate direction in 1/4” intervals.

Blasphemy, I’m sure, but the desire to have a 50/200 zero for TSHTF doesn’t outweigh the cost of actually traveling to an outdoor range to do it.

The more likely concern is hold overs for sub 25 yard distances, which I can do in my local indoor range. Since in the extremely unlikely event I’m going to use an AR for realsies, it’s going to be up close. So I’m thinking of 25 yard zero plus a few clicks TBD, then review holdover data.

Anyone else do something like this?

Just use these instead. https://www.m4carbine.net/showthread...M855-and-Mk262

[frozentundra]

Here's the ADVANCED version of what I was talking about before. It will help you zero your carbine to the fall of gravity at 200+ yards if your optic has vertical and horizontal stadia. Also great for checking your BDC or generating DOPE at longer ranges.

It's ADVANCED because it's as big as you need it to be, self-leveling, foldable for storage, and, as you can see, it even helps you change your oil! It requires only carboard, tape, string, a stick, and a rock to build if you are really hard up and don't have a pencil, level, or tape measure.

1) Use the string to make sure your tape is running straight. If you are rich, a chalk line, level, or pencil can make this even easier!

2) Use the stick as a story pole by wrapping some tape around it at any old distance that seems appropriate. Mark this distance from plumb line with more tape in two spots. Just make it the same and be precise for goodness sake; this is a precision instrument we are building here. Again, tape measure and pencil will help if you are wealthy or cannot source a stick. Otherwise, cut some cardboard and use that for a story pole if you own a knife or scissors but not sticks or tape measures. You can do this!

3) Tape a rock to the string and then tape the string to your top leveling mark. Be careful to do it at the correct length or you will surely feel silly. You should probably run the string over the top and tape it to the back of the target also because rocks are really heavy.

3.5) Add some horizontal tape. Level it with a level, square, or Pythagoras can help you if you must. Or don't level it and just use the vertical line for gravity, I won't tell anybody.

4) When you hang the target, make sure to tilt it a few degrees forward so your rock doesn't rub against the cardboard causing poor calibration of advanced self-leveling technology. If you can't figure out what this means without a picture, then this whole scope zeroing thing was never really going to work out for you anyway. Sorry about that. At least you tried!

5) Fold for storage.

6) Unfold and change oil.

7) Bonus sniper points if you tape your stick and a ribbon to the target for wind calls.

Pictures for reference:

[frozentundra]

Perhaps we should make this into a PF branded DIY kit and see if Larry Potterfield will let us sell it on Midway. If we can get Hickock45 to make a video we will all be rich.