Zen of the 100 Yard Zero

[a0cake]

Jack, good job getting this all down on paper and consolidated. As you know I'm also a firm believer in the 100M zero, so this will be a good resource for guiding people this direction in the future. Thanks.

[bp7178]

I think if you're breaking your stock/cheek weld and reloading the rifle every shot, you are potentially introducing inconsistency.

As a counter point, I doubt you would notice tighter groups due to barrel heat, but probably because you have less eye strain and you are breaking your focus and allowing your eyes to relax between shots while loading.

I see everyone (almost) in this thread referring to everything in meters. I haven't been to a LE or civilian gun range ever that is run out in meters.

I think its worth noting that yards and meters aren't the same thing, as we all know, and the farther out you go the bigger the difference gets. We think and write everything in MOA, how many fractions of an inch per click etc. I think a lot of people write/speak meters without making the distinction.

I really like 10 round groups to confirm zero with, depending on the ammunition. If you are shooting match ammo, and its a very consistent 1 MOA rifle/ammo combo, you can get away with less than 10. If you are using a 2-4 MOA rifle with 2-4 MOA ammo, your 10 round groups will largely be very consistent, albeit on the large side, which is fine.

I see guys at the range shoot a good 5 round group out of many, then quietly chalk the bad up to shooter error and get frustrated. When in reality, the groups aren't consistent due to shooter error, but due to lack a statistical significance with low count groups.

Its that consistency in group size that allows you to accurately know the center of your group and adjust accordingly. That is the one thing I've noticed when I went to ten round groups, all of the sudden I'm MUCH more consistent.

The take away, CONFIRM your zero with a 10 shot group at a minimum.

[Littlelebowski]

Needs to be stickied.

[SMETNA]

Yeah, this thread needs some of that hot sticky stuff

[bwhamilton]

this is amazing jack, thanks!

[SMC527]

Seems like that might get confusing. There is another thread on the 50/200 zero.

It could certainly go in another thread.

It was just very easy to visualize POI with those diagrams, so I was requesting a set for 50/200 from the OP.

[Raven Armament]

So optic zeroed at 100 and irons 2 in high at 100? I'm a little confused when the irons are discussed. With a 100 zero, I assumed it was both optic and irons at that zero.

[Failure2Stop]

So optic zeroed at 100 and irons 2 in high at 100? I'm a little confused when the irons are discussed. With a 100 zero, I assumed it was both optic and irons at that zero.

You can go that way, and out to 100 it works just as well, but the trajectory past 150 starts to get well enough behind and below the FSP to make it difficult to achieve consistent good hits on anything but large stationary targets.

It isn't an issue with the zero, it's simply the nature of the beast with irons. Optics generally do not have the issues with target obscuration and non-target focus, which makes them easier to apply offsets.

If you do not have a need to shoot past 125 meters, I would not argue with having both sighting systems on the same (100 m) zero. I like to shoot out to 300 whenever I can, and zeroing irons 2 to 3 inches high at 100 lets me do that without needing to adjust my irons.

I'm thinking about throwing another article together discussing the irons and the method to my madness. One of the reasons that I haven't is that Paul Howe already wrote about his method (3" high at 100) a few years ago (check CSATs website or do a search here and it should pop up), and like most things that Paul Howe writes it is concise, simple, and well illustrated. It was reading his article that pushed me to reevaluate what I was doing with irons.

Another reason to do a 2-3" high at 100 meters is that it works well with an IBZ setup rear sight, so you retain the range capability of the A2 style rear sight or other range/drop compensating rear sights like the KAC and Matech.

Sent from my DROID RAZR using Tapatalk 2

[Rodgerk]

Indeed a great article. Jack - is this any different from the long standing practice of many of us big game hunters to sight their 30 caliber class hunting rifles in to shoot around two inches high at a hundred yards and thereby be reasonably assured of hitting a vital zone out to around 250 yards and the bullet staying inside a "tunnel" of around 5" from the muzzel to the target? I have sighted my '06, 270's, and 308 in to hit at "2 high at a hundred" and have been in good shape out to a range beyond which an ethical hunter rarely takes a shot, generally speaking.

I just acquired an M4 and immediately sighted in at 2" high at a hundred and it occurred to me that it would take care of business as far as my eyes could make out a 5" strike zone in any event.

[crh]

zeroing irons 2 to 3 inches high at 100

What's your method for aiming with irons at a 6-8" black target at 100 yards? Do you place the top of the front post right in the center of the target? I'm finding that a bit difficult to do, but probably just need more practice. A 6 o'clock hold (dotting the i) is a bit easier, but then that makes things confusing as you change ranges.