Zeroing is an Ongoing Process?

[queenofcalifornia]

In this video, Chuck Pressburg reports frequently putting clicks on his fighting rifles to refine his zero:
https://youtu.be/kQj6JiWyslc?si=fgldvyBjkbSagz5W

Questions:

• If zero is a mechanical alignment between a rifle and its sighting system, why and how do things like clothing, shooting position, lighting conditions, gun mount, cheek weld/head position, etc. change the point of impact to where adding/removing clicks is needed?

• If zeroing is an ongoing process as Chuck says, how do you take a good cold bore shot if the point of impact changes so often?

• Bonus question: On a rifle, does resetting the trigger in recoil have any effect on accuracy or consistency compared to pinning the trigger rearward until the sights settle?

[Noah]

When I shot rifle way more often, I’d find myself adjusting my zero a click or two or three every range trip. Number one cause was probably shifts from temperature and pressure affecting velocity.

Also sometimes see a small shift from shooter to shooter with the same rifle, or kit vs no kit- as you imply, that can only be the result of human error in input.

I only shoot rifle every other month or two now and mostly leave my zero alone.

[cosermann]

Zero is not merely a mechanical alignment of the sighting system and rifle independent of other factors.

Temperature and pressure (already mentioned), humidity, different loads, different lots of the same ammo, etc. are all factors. Depends how much accuracy you're looking for/need. If one is trying to hit a plate at 50 yards it doesn't matter much. If one is trying to hit a smaller target at extended ranges, it all matters.

My last zero on several rifles was last winter. Need to get out on a nice day this spring and tweak the zero for the summer.

[Shawn Dodson]

Nevermind.

The comment I was going to make is already mentioned in a previous post.

[Skinner Precision, LLC]

In this video, Chuck Pressburg reports frequently putting clicks on his fighting rifles to refine his zero:
https://youtu.be/kQj6JiWyslc?si=fgldvyBjkbSagz5W

Questions:

• If zero is a mechanical alignment between a rifle and its sighting system, why and how do things like clothing, shooting position, lighting conditions, gun mount, cheek weld/head position, etc. change the point of impact to where adding/removing clicks is needed?

• If zeroing is an ongoing process as Chuck says, how do you take a good cold bore shot if the point of impact changes so often?

• Bonus question: On a rifle, does resetting the trigger in recoil have any effect on accuracy or consistency compared to pinning the trigger rearward until the sights settle?

Question one- because if you keep track of your data, you will see trends in the differences between mechanical zero and positional zero. It is very common for NRA/DCM high-power shooters to have a different zero for the 200yd offhand event than the 200 yard sitting rapid event. Additionally experience and tracking zero data will teach you how much lighting affects things (hint "lights up, sights up"). The simple why is, the changes in the interface between you and the gun matter....

Question two- context dependent on the application, the cold bore shot for some shooters is the most important, for others it is a "fouling shot" before getting serious at setting a record. If it is important, you better be collecting data, preferably with a larger data set and varied conditions

Question three- again context dependent. A 10M ISSF / Olympic air rifle shooter's follow-through requirements are different than a short range BR shooter "free recoiling" or a 3-gunner smacking plates offhand at 300 yards...some rifle systems (i.e. large frame AR's) have a combination of recoil and reciprocating mass that make them less forgiving of trigger manipulation

[okie john]

I feel like we’re missing some context here.

The speaker in the video is a former Tier-1 guy with almost superhuman shooting ability and a very realistic understanding of what he and his gear can do on command.

When most people try to quantify what their gear can do, they use group samples that are too small. In testing rifle loads, they stumble into one tiny three-shot group and declare victory. Then they zero with more three-shot groups. Almost all of these groups will be bigger than the one freakishly small group, but they ignore that. POI will also differ, so the few of them who understand and care about zero will chase it all over the paper with more three-shot groups. I did this for years and I’ve seen it hundreds of times when I worked on commercial ranges.

None of us ever had a clear idea of what we or our rifles could do on command, and we were full of shit if we told you otherwise.

Instead, shoot a 10- or 20-shot group, adjust your sights, then shoot more 10- or 20-shot group to confirm. Repeat until the group is where it belongs. A lot of “0.5 MOA” rifles become 1.5 MOA rifles, but any shot that hits within the footprint of the larger group really is zeroed based on the gun’s actual capability.

The proverbial

good cold bore shot

depends on actual target size. Outside of competition and varmint hunting, few people engage tiny targets at long range. On a person, the vital zone about the size of a grapefruit, and engagement distances are usually shorter rather than longer. The vital zone on a deer is about the size of a toaster. On an elk, it's bigger than a watermelon. On a moose, it's as big as a laundry basket. Ranges on game are usually around 175 yards if not much closer, and the bigger the animal, the shorter the range (usually).

Once you combine these two bits of knowledge, you'll have a realistic idea of what your gear can do on command. Then it's time to focus on marksmanship. Once you're getting good hits at speed, then you can start to adjust zero in response to other stimuli like the guy in the video.


Okie John

[GJM]

When I put a new optic on a handgun that I care about, like a competition pistol, I expect to refine the zero over four or five shooting sessions to get a zero that I am happy with, before I witness mark the adjustment turrets. I have also observed my zero change as my technique changed overtime. That is all using the same ammo, and not considering a load change.

[Clusterfrack]

Interesting topic. I'm going to send a possibly spicy response below!

A confirmed zero is important in all guns, and essential in precision rifle shooting. But I'm skeptical about this approach for a few reasons.

Zeroing requires stable, repeatable conditions. Deviations from zero can be caused by factors other than the mechanical zero and ballistics. Especially in a long gun, I'd be reluctant to change my zero unless I can control the conditions. If I had reason to think that the mechanical zero was jacked, I'd have no alternative than to do my best to get a field zero.

I have not changed the zero on my main precision rifle (S&B PM2/AIAE .260) in years. The effect of atmospherics is accounted for in my ballistic software. Of course, I'm not shooting F class where tiny changes make a big difference.

On carbines with LPVOs, I have not observed changes in my zero above the 1/2 moa range. On carbines with dots, the zero is stable within my ability to measure it.

I do not adjust my zero based on my technique (or position like prone, bench, etc). I zero in a consistent way, and rely on that consistency.

@Cdub_NW, @JCL any thoughts?

[Clusterfrack]

Bonus question: On a rifle, does resetting the trigger in recoil have any effect on accuracy or consistency compared to pinning the trigger rearward until the sights settle?

Pinning the trigger can be a cue to "follow through" on a shot. It helps some people to not push into the gun, stay visually focused on the target, and call the shot by watching the reticle/dot lift and return.

[Skinner Precision, LLC]

I have not changed the zero on my main precision rifle (S&B PM2/AIAE .260) in years. The effect of atmospherics is accounted for in my ballistic software.
@Cdub_NW, @JCL any thoughts?

Your example AI /SB combo is the opposite end of the spectrum from my positional example. The context of mine involved decades of high level shooters experiencing 1/2- 2+ moa shifts in zero between 200 standing and 200 rapid sitting BUT they were using irons (more head position susceptibility, call it parallax if you want for sake of conversation) AND they are using their body solely for support with radically different buttplate / shoulder interface between positions along with differential placement of head on stock and probably most importantly often vary different amounts of cant on the gun for stability between standing and sitting BUT they are doing it consistently. With your rifle system, those variables are minimized when shooting off a bipod or other supported position.

In my opinion, LPVO carbines are somewhere in between a precision rifle (where after establishing NPA there is often minimal difference between positions)and a position rifle in regards to the shooter influences on where the bullet lands. LPVO carbines are more susceptible to shooter changes than a precision rifle, yet they are also often employed on targets and with shooter expectations that make the changes immaterial, which gets back to context of what we are doing with the rifle probably dictates if chasing zeros matter....