Advanced Marksmanship POI variance from shooter to shooter

[zeroz]

I never realized how different a zero one person could shoot from another on the same scoped rifle. I have set up a few hunting rifles for people and they have always been pretty well on for them. I set a buddy up who is getting into hunting and is a fairly new shooter that I have been working with. His zero was a little over a minute and a half low of mine.

My first thought was that he isn't getting behind the scope straight. I tried asking him questions, if he has a black edge on the scope view, etc. We worked on it and still he was 1.5 low, consistently. Bottom line was, he was shooting (mostly) consistent moa groups from prone with a bipod so we adjusted his zero for him. He said he wasn't going to shoot over 300 at an animal and was getting solid hits on a 12" plate out to 400 so I called it good for hunting season and sent him off.

This made me think of a time several years ago when a guy I was hunting with smacked his scope one morning. He didn't trust the gun, had forgotten his backup rifle and we didn't want to shoot in the dark that morning to check. I was done hunting so he carried my rifle. We got into elk that were 500 out and we were stuck there due to terrain and time constraints of the elk feeding toward private land. He is a very good shooter. Shot high-power for years, shoots all the time, etc. I absolutely had confirmed dope (at close to that elevation, etc) out to 850, for me. 500 should be an easy shot for him. Dead calm, solid rest, perfect conditions. Missed just low. I called the shot, he said it felt good. He aimed top of her back and killed the cow with a fairly high double lung shot, about 10 inches down from her back. We dealt with the animal, packed it out and left the next morning. We never ended up talking about the shot, rifle, etc.


What experiences do you have with this and what explains it? Both guys are quite a bit bigger than me.

 

[Dthomas3523]

Sounds like they both may be managing the recoil a little better.

 

[sled_mack]

What about vision differences and using corrective lenses? I’ve seen offsets like you described when swapping rifles with others.

Worst case- I’ve got one buddy that when I shoot his rifle my impacts are 5 inches right. WTF is up with that, I have no idea?

 

[kthomas]

This was incidentally tested at Rifles Only when I attended a PR1&2 course.

There was only 6 of us in the class, and there was a wide range of rifles. Couple of us had custom GAP's, one had an AI, one a Savage, one a Remington, etc. There was a couple of guys that were interested in trying out some of the other classmates rifles there. We all agreed (easy being just the six of us) and we lined up on the 100 yard range and shot 5 rounds out of each rifle.

The results were really interesting. This was near the very end of the week of training, so each rifle was zeroed to it's owners shooting. A few of us had the exact same zero. Some peoples were way off - they would be off with your rifle and you would be off with theirs. It was pretty eye opening to see how big a difference there could be, I think even Jacob Bynum was a bit surprised.

I saw it again last year, actually with one of the guys from the training class mentioned above (a few of us remain good friends and try to meet up yearly to shoot). Last year prior to the Quiet Riot, we took our rifles to a nearby range, ensured our rifles were zeroed and then got some data out to 1,000 yards (I was running a fairly new barrel at the time, along with a suppressor which I never shoot). He consistently shot my rifle low. I would make impacts on an IPSC sized target at ~1,000 yards, and with him using the exact same dope on my rifle he would miss the target low.

If you set up behind the rifle identically (or close to it) and apply the fundamentals more or less the same, the POI for two shooters on a rifle should be really close, if not identical. If you load the bipod different, if your trigger pull is different, etc., you are going to see that difference on target. Hell, I can change my own POI by 0.5 mils or more just by changing the way I load the bipod.

 

[zeroz]

This is all interesting, thanks for your replies. It is especially interesting that you would see the same impact shifts between two guys guns. Sounds like you would either both have impact shifts on each others guns or neither, which is good for consistency. It would lead you to believe that it is at least repeatable and something you could learn about each others rifle if you needed to.

I thought about vision, but mostly eye relief distance but you wouldn't think it should matter if you're straight behind it.
You'd sure like to think getting behind a zero'd rifle with good fundamentals would get you hits on target but it just isn't so. Shooting is such a bitchy mistress. I remember Hathcock talking about in his book how him and Burke shot the same zero so it was easy for them to share a rifle. I kinda always wondered about that as I had never experienced it until that day hunting. It didn't lead to much thought until I was dialing in that rifle for my buddy where it became very evident. Big POI shifts like that can make a gun damn unusable (at least for first round hits) unless you know the shift and know its consistent.


Sled, when he shoots yours is he 5 inches left?

It would be interesting to see how consistent is it. I bet it runs the gamut depending on how consistent the shooter is. I'll end up working with the new shooter some more this summer. I'll see what kind of consistency there is between us, small sample but interesting nevertheless.

 

[Steel head]

I see this a lot.
recoil management and gun positioning.
cheek shmushers and flinchers.
trigger smashers and and bad hand positioning.

 

[sled_mack]

@zeroz
He impacts left on my rifle, but not nearly as much. More like 1.5 inch. That’s what struck me as odd- why not the same distance when he shoots my rifle?

 

[RTH1800]

Like every shooting variable, the lighter the rifle and the higher the recoil impulse the greater the effect. ie, 8# .338 will show more variation than 16# 5.56.

When you fire you energize the entire system. The more difference in recoil impulse, the greater the variation.

 

[wade2big]

What about vision differences and using corrective lenses? I’ve seen offsets like you described when swapping rifles with others.

Worst case- I’ve got one buddy that when I shoot his rifle my impacts are 5 inches right. WTF is up with that, I have no idea?

Bifocals? My step-mother shoots damn near that far off when she shoots any rifle but hers. She where’s glasses and that’s all I can come up with. She definat ly has to sight in her own.

 

[Precision Underground]

Every time your shoot a rifle the stock WILL deflect the instant you pull the trigger. This will affect where the round lands and will determine your zero. This is why a relaxed and repeatable position is so important. People who can’t be consistent will have a hard time shooting a good group and may have a different zero every time they shoot. Sound familiar? “Man my scope is wandering”. So it is a for sure thing that different shooters may have different zeros.

 

[sled_mack]

Bifocals? My step-mother shoots damn near that far off when she shoots any rifle but hers. She where’s glasses and that’s all I can come up with. She definat ly has to sight in her own.

I’ve got astigmatism and bifocals. He’s got cheaters for reading. Neither of us are adjusting the ocular focus when just trading rifles at the range. So lots of possibilities for the offset. But the magnitude is what surprised me. I’ve never been that far off with someone else’s rifle.

Agreed that recoil management is a big factor. I can tell when my mental focus isn’t what it needs to be. No scope zero adjustments on those days.

 

[Steel head]

Every time your shoot a rifle the stock WILL deflect the instant you pull the trigger. This will affect where the round lands and will determine your zero. This is why a relaxed and repeatable position is so important. People who can’t be consistent will have a hard time shooting a good group and may have a different zero every time they shoot. Sound familiar? “Man my scope is wandering”. So it is a for sure thing that different shooters may have different zeros.

I’ve seen that a lot in myself and others thankfully not so much in myself anymore.

The person I shoot with the most now I can get on his 338 and easily get hits with his call outs and He on my 260(Buttercup) and 7 saum(Surrey Girl) with my call outs.

Some of the newer shooters I shoot with are getting there.

 

[Mendoza0311]

The first time I noticed this was about two years ago I bought a youth rifle for my son Remington 700 chambered in 7mm08 I mounted a brand new scope bore sighted and shot at 100 yrds to sight in with nosler factor ammo. I shot a three shot group to confirm however when my son shot he shot to the right and about two inches high so I told him to shoot a group and all three were touching high and the the right. still to this day when he shoot my rifle his groups are just a bit lower than mine roughly 1.5"-2" I just thought maybe its the way he lines up behind the scope cause of the difference in his cheek weld compared to mine. IDK