Range Report Acceptable/normal zero variation

[jaybic]

Hello,
Just for curiosity sake, I am wondering what folks consider a "normal" amount of zero variation. By that I mean that I may have my rifle perfectly zeroed to knock the bullseye out of a target and then check zero at a match and see it be .10 or so high, low, or L/R. I know how a person addresses the rifle can play a roll on this as well as a number of other variables but just wanted to collect thoughts from others on here as to what they think is common or at what point I should consider adjusting zero.

I have also seen my zero to be off, adjusted it only to find out that now it is off the other way, at which point I should have just left it alone to begin with. How does one get to the bottom of this?

thanks,

jamie

 

[Dthomas3523]

I wouldn’t mess with zero if it’s within .1 (maybe even .2).

Mirage
Light refractions
Shooter (position and setup)

An all easily account for .1 difference.

To alleviate mind fucking myself, once I get a new rifle or change something (barrel, pull apart to clean, etc) I will zero the rifle as close to perfect as I can. Then I don’t touch it or even check it until I change something again. The rifle has already been checked to make sure zero doesn’t shift (if it does, it needs bedding or whatever component is broken/loose is fixed). There’s pretty much no reason a properly set up/working quality rifle system should lose it zero.

Now, if I’m noticing a trend at a match, I’ll go to zero range and maybe adjust it. This almost only happens if I just zero’d the rifle the day before. I chalk those up to lighting/mirage, or possibly I didn’t get the zero done properly with bad position.

 

[Dthomas3523]

So, a simple answer is:

A properly working rifle system should have zero change in zero. Key work is “working.”

Several things can affect your zero that are not the fault of the rifle system.

 

[jaybic]

So that jives with what i was thinking. it is a 6BRA and it never really strays farther than .1 so seeing some small shift that can be chalked up to the other things you mention makes me feel more confident. I have been thinking about making a "zero log" target with multiple dots on it so i can track where it shoots zero on any given day and circumstance just so I have a history on it.

 

[Dthomas3523]

I clean quite often.

If I didn’t I would use an “evolving zero.” Basically small tweaks each range session until its in an area I’m confident in and wouldn’t mess with it after.

 

[jaybic]

I typically clean every 300 rounds or so. I fear carbon rings and things like that so I have found my guns tend to shoot better and more consistently than the old "let it go until accuracy falls off" method. Tried it what way and it didnt go well....

 

[ma smith]

The rifle has already been checked to make sure zero doesn’t shift ...

is there a a quick summary of this test (or links, etc) for those of us who are new?

 

[jaybic]

what do you fellas use for a protocol or a procedure to "prove" the rifle is established and doesnt shift? I am thinking a 2x2 piece of cardboard with like twenty five 1 inch dots on it and shoot one each time I go to the range, from prone. Keep track of time, date, wind and environmental conditions so I can see if there is a pattern....thoughts?

 

[Dthomas3523]

Perform tall target test on optic.

Bolt everything in.

Zero rifle

Beat the shit out of it with dead blow hammer, slap it around, or toss it on ground a bit.

Check zero. If there is a shift, do it all again. If it’s another shift, then start diagnosing what it is. It’s usually needs bedding when this happens.

 

[jaybic]

you seriously beat on the scope with a plastic hammer???

 

[Dthomas3523]

you seriously beat on the scope with a plastic hammer???

And the rifle. Not much point of paying $5-10k+ for a rig that can’t take a few love taps.

What do you think will happen in a match on a barricade made out of steel when you accidentally ram it into the side?

 

[1moaoff]

When time allows zero process.
Develop load on broken in barrel.
Zero rifle from prone
Shoot another 10 rounds from prone, breaking position each time.... this includes picking up the rifle, stowing bipod, pulling mag.

Next when going prone I deploy bipod roughly and quickly I frop the rifle onto bipod and surface im shooting from and run it as normal. I may also butt or muzzle drop it on wood.

Then at a later day I will intentionally do the same.

If it survives and zero is good I won't touch it unless a change is made to the gun.

Buy quality gear, test your gear, trust your gear!!

 

[Crews]

I keep 3x5 note cards with a single 1” red dot in my data book. Each time I go shoot I put a new card up and check zero first before I move on to anything else. This allows me to identify if and how much it’s walking around over time for a given rifle.

it’s also just a good exercise to make me focus on it instead of assuming.

 

[1moaoff]

Also fwiw...
The human behind the rifle has more variables than the gun. Clothing, mood, joints,muscles, bloated from too much food, hot cold, etc.....

I always start a training session with a 5 round group. It's a zero check and me check.... guess what happens when I'm off.... my zero is off.
The guns zero is still on but I'm not!

I'm not saying to never adjust it but i am saying don't chase it.

I have been at classes and seen so many guys talk about needing to adjust zero all the time. Usually they have to adjust every day.... why??? Because normally they are changing as a shooter. Its annoying and comical at the same time. On a line and every morning its the same 5 guys that need to adj..... instructor gets behind rifle and it prints the same as day before.
A solid rifle, solid ammo, = consistency

 

[Mordamer]

Didn't read the rest of the replies.

I usually put up with .2 Mil variation if some of the variation is confirmed by my kestrel. I usually don't see more than plus minus .1 Mil vertical variation with my zero at 100 yards.

I have had multiple times where I went to a match and checked zero at the range day and adjusted by a click or two. Then day 1 of the match I had to reverse that adjustment. Now if I go to a range day and I'm within .2 Mil I ignore it.

 

[ScottDWallace]

What do you think will happen in a match on a barricade made out of steel when you accidentally ram it into the side?

Which WILL happen. With nice gear comes peace of mind.

Had a stage where I was on deck and my rifle was sitting off to the side in some sandy dirt, staged and ready to go. Another shooter accidentally knocked the rifle over and in hollywood like slow motion, I watched the rifle tip over, bipod leg flip an impressive amount of sand and silt into the air, then right into my action. Scope was covered in the crap and would crunch with every turret movement. Stage turned out to be a shit show thanks to me acting like a god damned monkey trying to clean my gun right as the timer went off. Gun ran great, even full of crap (less than ideal for the chamber, obviously). When I got home I gently blew the scope off with compressed air, and hit the chamber with some JB's and she was good as new.

 

[jaybic]

Thanks for the replies folks, I have chased my zero all over the place and it appears I may have been doing myself more harm than good. Just for some back story, I am running an Impact 737 with a Spuhr 4001, Vortex Razor Gen II in a McMillan A3-5(is not yet bedded in to the stock) chambered in 6BRA so I would hope that from a component standpoint I am all good to go I guess....other than beating it wait a plastic hammer(gonna be tricky talking myself into that but its the only way to know i guess).....andway...thanks for all the good ideas folks,

take care

Jamie

 

[Deleted member 113831]

Thanks for the replies folks, I have chased my zero all over the place and it appears I may have been doing myself more harm than good. Just for some back story, I am running an Impact 737 with a Spuhr 4001, Vortex Razor Gen II in a McMillan A3-5(is not yet bedded in to the stock) chambered in 6BRA so I would hope that from a component standpoint I am all good to go I guess....other than beating it wait a plastic hammer(gonna be tricky talking myself into that but its the only way to know i guess).....andway...thanks for all the good ideas folks,

take care

Jamie

I'm careful to zero my rifles in neutral light. This means heavy overcast, or as early as I can see the target in the morning. That way I can be reasonably sure there is no built in offset from lighting conditions.

The other way is the opposite extreme. You zero when the sun is high during a condition approximating your most prevalent average condition.

 

[FishDr]

what do you fellas use for a protocol or a procedure to "prove" the rifle is established and doesnt shift? I am thinking a 2x2 piece of cardboard with like twenty five 1 inch dots on it and shoot one each time I go to the range, from prone. Keep track of time, date, wind and environmental conditions so I can see if there is a pattern....thoughts?

This would be a good idea, and I have an additional question. Do you perform this test on cold bore/cold shooter? Or should it be done after your first fouling shot? Some rifles tend to shoot closer to zero after the first shot, and guys map / track the cold bore shot. My experience in MY rifle that was properly beded and assembled was the cold shooter was more to blame than the cold bore. Yes, the condition exists, but the variation IN MY GUN was much more attibutable to me as a shooter than the gun. I chased zero for a long time due to this, and then started adjusting a zero only after a change in the platform, and only after I had warmed up a bit.

 

[jaybic]

I havent actually tested in this format yet but I think it would be good to include a cold bore shot and even a clean cold bore shot in the test....

 

[Dthomas3523]

Here is one of my rifles. I zero’d after putting about 10 rounds on the barrel. Just used 30gr of varget and I have a tuner that hasn’t been adjusted since before barrel speed up and such.

This is with 200+ rounds. Mostly all barricade and off rocks for practice. Some tank traps. In the floorboard of back seat of truck *without* a case. So it’s been tossed around and bounced around a couple weeks.

I wouldn’t have an issue shooting a match with this zero still. Might make a mental note if there is a 100yd paper stage at dots, that’s about it. If I take it out again in a week and it’s about the same, I’ll adjust up .1. Maybe right .1, but probably just the up. Sun is also in my face pretty bad. So I wouldn’t mess with it just from this sample.

 

[Ledzep]

I've done a lot of 20-50 shot groups over the last year and a half or so. I'm able to track each shot, then plot them in Excel. The difference between the first 5 shots and the final 20-50 shot group for mean point of impact can be over .25 MOA.

Most people don't understand that there is a random distribution of shots going on and while your rifle commonly prints 5-shot groups sub 1/2 MOA for an extreme spread between the 2 farthest apart, if you were to shoot more rounds you'd find that most good barrels are in the .75-1.25 MOA range, and the real mean point of impact in the middle of that cone can be slightly different from your various 5-10 shot groups' MPOI. The 5-shot group can be dead nuts on, it can be .3" off at 100yd, or anywhere in between. You don't know until you fire more shots.

Once you fire a 20-30 shot group, adjust zero to that MPOI, then understand the true dispersion of the rifle/ammo, there is a lot less "zero shift" going on, and more "rounds landing within the predicted cone of fire". YMMV.

Not worth ignoring; light, wind, temp, and various other factors can also shift 100yd zeroes a tenth or two.

 

[Dthomas3523]

I've done a lot of 20-50 shot groups over the last year and a half or so. I'm able to track each shot, then plot them in Excel. The difference between the first 5 shots and the final 20-50 shot group for mean point of impact can be over .25 MOA.

Most people don't understand that there is a random distribution of shots going on and while your rifle commonly prints 5-shot groups sub 1/2 MOA for an extreme spread between the 2 farthest apart, if you were to shoot more rounds you'd find that most good barrels are in the .75-1.25 MOA range, and the real mean point of impact in the middle of that cone can be slightly different from your various 5-10 shot groups' MPOI. The 5-shot group can be dead nuts on, it can be .3" off at 100yd, or anywhere in between. You don't know until you fire more shots.

Once you fire a 20-30 shot group, adjust zero to that MPOI, then understand the true dispersion of the rifle/ammo, there is a lot less "zero shift" going on, and more "rounds landing within the predicted cone of fire". YMMV.

Not worth ignoring; light, wind, temp, and various other factors can also shift 100yd zeroes a tenth or two.

While I agree with many of your theories, the most barrels are .75-1.25 moa barrels.....are you basing this off a bipod and rear bag, $1200 front rests and rear ear bags, or a rail gun setup?

The reason I ask is that every week at 1k yd F class matches, there are perfect 200 scores. And they are routinely shot by the same shooters (this would imply it’s not luck and random).

While some of them do purge barrels, most aren’t trashing most of their barrels because they won’t shoot consistently. These 200 scores are all moa at 1k and this is with wind and such (though the better shooters tend to only fire rounds when the conditions are the same as the past 10 ring shots unless forced to). With the changing conditions such as wind, mirage, lighting, etc......a barrel only capable of .75 just would not do this consistently. And many of these guys couldn’t afford to trash 9/10 barrels.

So, if the theory is that with a bipod and rear squeeze bag, I likely agree. If it’s with much more stable equipment, this theory is disproven week in and week out.

 

[Deleted member 113831]

@Dthomas3523
Come on brother, you know what he means. Replace the word "barrels" with the phrase "rifle/shooter systems" and it rings true like the gospel. We see it all the time in the reloading forum.

Somebody will post some series of 3 or 5 shot groups, and all will be sub-moa. But were you to do a composite of all the groups at same POA, the composite would look a lot different.

I don't consider specialized F-class, or benchrest, or even many of the specialized PRS guns to be representative of anything approaching practical equipment for practical riflery. What they are doing or accomplishing has almost zero effect for me. Some may disagree, that is their perogative.

 

[Dthomas3523]

@Dthomas3523
Come on brother, you know what he means. Replace the word "barrels" with the phrase "rifle/shooter systems" and it rings true like the gospel. We see it all the time in the reloading forum.

Somebody will post some series of 3 or 5 shot groups, and all will be sub-moa. But were you to do a composite of all the groups at same POA, the composite would look a lot different.

I don't consider specialized F-class, or benchrest, or even many of the specialized PRS guns to be representative of anything approaching practical equipment for practical riflery. What they are doing or accomplishing has almost zero effect for me. Some may disagree, that is their perogative.

He literally said barrels are capable. That’s a very big distinction from shooters are capable. I’m not going to assume he means one thing when he’s obviously more than intelligent enough to know that’s a huge distinction. Which is why I asked for clarification, with an explanation why.

 

[Ledzep]

I've done both. 1.250" Straight barrels in a hydraulic return accuracy fixture in a 200yd indoor tunnel, and 100yd groups in an indoor range bipod and bag with a typical PRS rifle. The shoulder fired stuff is .1-.2 MOA worse than the accuracy fixture/rail gun, even if you use the same barreled action and load. Seenthe same thing across a couple different (good) shooters.

Just because I say that the outside-outside dispersion is .75-1.25 MOA doesn't mean that 80% of the distribution doesn't land within .5-.8 MOA.

 

[Deleted member 113831]

He literally said barrels are capable. That’s a very big distinction from shooters are capable. I’m not going to assume he means one thing when he’s obviously more than intelligent enough to know that’s a huge distinction. Which is why I asked for clarification, with an explanation why.

Most people don't understand that there is a random distribution of shots going on and while your rifle commonly prints 5-shot groups sub 1/2 MOA for an extreme spread between the 2 farthest apart, if you were to shoot more rounds you'd find that most good barrels are in the .75-1.25 MOA range...

I chose to see the rifle...you chose to see the barrel.

 

[Ledzep]

I'd like to add, that shooting 20-50 shots in a group, while it obviously gives more definitive results than a 5-10 shot sample, does take longer to do. It's taken me the better part of a year to get past the initial exploratory testing, and actually into what would be considered a proper "OCW" test (testing the same combo with .3-.5gr charge weight increments), and I've only got it done for a couple of powders in 1 cartridge with 1 bullet so it should go without saying that there's a lot more to see. I can only report what I've seen so far with MY testing, and can't say anything about BR or F class because I've never seen it or done it. I'm isolating as much as I can to make the results useful. If that means that the 3rd variable that I test is the one that brings groups from .75-1.25 MOA down to .3-.5 MOA, then it will be a while before I find it. ETA: 35 shots entirely inside of 1.25 MOA is no joke. Inside of 1.0 MOA is great, and inside .75 MOA is insanely good. It basically means you'd almost never throw a flier outside a 1 MOA cone over the life of the barrel (obviously assuming ammo didn't have major defects, and ignoring environmental effects down range).

Nonetheless, for the purpose of this topic, .2-.3 MOA worth of zero wander as shot count increases is fairly common. 15-20 shots usually levels it out to "close enough" of the final MPOI.

 

[jaybic]

Perhaps I am putting my ignorance on display but think I am going to have to try this...shoot a group of 20 plus shots and find the center of that, and relocate that "center" to as close as I can get to my POA and call it zeroed. That way the dispersion cone should fall either in the zero or immediately adjacent to it ...hell, I dont know but it seems sensible to me.....thanks fellas!

 

[Dthomas3523]

Perhaps I am putting my ignorance on display but think I am going to have to try this...shoot a group of 20 plus shots and find the center of that, and relocate that "center" to as close as I can get to my POA and call it zeroed. That way the dispersion cone should fall either in the zero or immediately adjacent to it ...hell, I dont know but it seems sensible to me.....thanks fellas!

I do something similar. 10-20 shots. But one shot at each sticker.

It gives me an aim point each time and I can look at them and see about the same thing as a single group of 20.

 

[jaybic]

I agree. I have done the 1 shot per dot thing and I think it's a good idea because on occasion, one shot will take out your aiming point and potentially skew follow up shots, so using one shot per, a person always has a fresh poa...it doesn't necessarily show group most accurately I guess but does give a solid impression of zero and shot dispersion around it.