Cold bore zero versus (very) Hot bore zero “test”

[5811]

Some of you guys are over thinking this wayyyy too much. The simple fact that he’s dealing with mirage eliminates any “definitive” results within a statistical method as defined by pointy heads. He clearly illustrates his objective, which is to show that all the guys complaining about “hot” barrels affecting POI and groups are full of crap unless they’re shooting junk barrels. At some point, he’s going to say “WTF” when dealing with this crap and stop wasting time and money on providing useful information. Let’s be honest, where else are you going to get real world useful information that relates to the way most of us shoot other than on this forum?

I don't think there's any harm in asking questions. It gives the person doing the work a chance to defend their methods and conclusions or refine them in the future, and allows others to have a greater understanding. I think if the original post got 2,500 "likes" and no follow ups, everyone would lose. Plus, this is social media at the end of the day. Interactions are $$.

I would have liked to see a few more magnums in thin barrels and the recorded temperature data. Then we could try and extrapolate the results to zeroing a rifle in winter conditions vs what they were in the test. I dont think it detracts from the methods to ask about heat sink into the round or what might be different if the ten hot-shots started after burning 3 into the dirt so all ten were truly hot instead of maybe 6-8. And its fair to look at the results subjectively and think if I did that test myself, I might be inclined to conclude that the majority of the groups opened up with a hot barrel, and the barrel itself might be a contributing factor with mirage and statistical dispersion.

But did I come away with a significantly better comfort level in shooting 10 shot strings to zero vs spending all day waiting for a barrel to cool? Absolutely.

 

[Marbles]

How is definitive not a concept in statistics or science? A definitive statement is a final conclusion with seemingly high authority or confidence.

One can certainly argue semantics on what is meant by definitive. However, when it comes to any conclusion there is a margin for error.

Good science does not prove anything, rather it fails to disprove. With enough failure to disprove we start calling things laws, but even these are not set in stone and if an experiment ever provides a repeatable disproof, even laws, are subject to be thrown out or held as useful, but not a complete description. Just look at Newtonian physics for such an example.

Hypothesis
-Good barrels have no shift in POI when hot.

Null hypothesis
-Good barrels shift POI when hot.

Based on this data and the predetermined definitions, we accept the hypothesis and reject the null. However, the possibility remains that another test may not confirm such a result. Of course, one can have statistically significant results that are not significant in life. Example, repeating the test with 100 round groups might show a POI shift of 0.04 mil, so there would be a shift, but given the adjustment on scopes no one could do anything meaningful about it.

Humans frequently rephrase things to a wording that sounds definitive/absolute/set in stone/Etc which is useful as it avoids needing two hundred words to say something, that is different than attaching a modifier that specifies that something is definitive.

 

[mt terry d]

I would have liked to see a few more magnums in thin barrels and the recorded temperature data.

I'd would like to see someone shoot a quick ten shot group with a 460 Wby.......and have a dummy round in #9

 

[HighUintas]

I don't think there's any harm in asking questions. It gives the person doing the work a chance to defend their methods and conclusions or refine them in the future, and allows others to have a greater understanding. I think if the original post got 2,500 "likes" and no follow ups, everyone would lose. Plus, this is social media at the end of the day. Interactions are $$.

I would have liked to see a few more magnums in thin barrels and the recorded temperature data. Then we could try and extrapolate the results to zeroing a rifle in winter conditions vs what they were in the test. I dont think it detracts from the methods to ask about heat sink into the round or what might be different if the ten hot-shots started after burning 3 into the dirt so all ten were truly hot instead of maybe 6-8. And its fair to look at the results subjectively and think if I did that test myself, I might be inclined to conclude that the majority of the groups opened up with a hot barrel, and the barrel itself might be a contributing factor with mirage and statistical dispersion.

But did I come away with a significantly better comfort level in shooting 10 shot strings to zero vs spending all day waiting for a barrel to cool? Absolutely.

Absolutely correct! I know I won't be worrying about it anymore... Those three guys are definitely far better shooters than I am, so if they can't detect a shift in POI that's outside of the variation of a 10 shot group, I definitely can't

 

[Formidilosus]

Good explanations. Thanks. I understand what you are saying about natural and random variation in group sizes regardless of barrel temp, but is it not at least somewhat telling that the groups here do tend to consistently open up with heat?

The tend to, however it’s just the noise from small sample sizes and it trended that way for this relatively small population of shots. Four of those rifles are mine that get used heavily- two did not open up at all (#8 and 10) and the two that showed that they did, is just due to small sample sizes for gun #7, and gun #4 had the action lossen and the group kept dropping lower in target as I shot. After tightening the action screws on #4, the very next ten rounds (so hot group) was about 1.5 MOA with the same ammunition- so smaller than the original cold barrel group.

Here is rifle #4 cold and extremely hot shots overlaid with different ammunition on another day-






Gun #7 is the 308 used for the scope evaluations- it has hundreds of groups from cold and hot barrels on this forum, it has zero change cold to hot. Again, here is it with different ammo on another day with cold and hot overlaid-




To detect minute changes, and in this case it’s changes that fall outside the expected variability (which did not happen with any rifle here) you need a much larger sample size. It would start at 30 shots per rifle, per group to get to 95% confidence, and really we would need multiple groups from each. It becomes prohibitive quickly, and quite frankly digresses into irrelevancies for any practical use.

We could repeat the experiment a hundred times over with the same targets, and at the end of those 100 groups the two groups, cold and hot, would look identical. They would be a near perfect circle with a large hole in the center and less shots the farther you move from center. It’s been done consistently.


These are both the same rifle with different ammunition, human fired from sandbags, using an Oehler and acoustic to track and log each shot. 100 shots per group. There are a bunch of cold barrel shots, a bunch of extremely hot barrel shots, and a bunch in the middle- about a third for each. The difference in cold barrel 10 round group size and location between cold and hot was less than 1/10th on an MOA- totally inside of random distribution.

Yes, that could be mirage, but mirage is also a byproduct of heat. So it seems one could say that heat CAN (not necessarily WILL) open up groups, even if mirage is the true culprit. Mirage wouldn’t be there if not for the barrel heat. Which is then perhaps to say that when shooters state their groups often open up with heat, it’s not all “nonsense”? It can happen. It’s shown here.

Yes you can say that, however that is not why or what people say. Mostly people use a barrel heating up as an excuse for why they don’t shoot more shots to check zero and to confirm group size. The “the only shot that matters is the cold bore, and the first shot always lands into the same spot”. It’s simply not true.
These statements are made by and large by people that do not have anywhere near sufficient data to come to that conclusion. The only way to see a minute change with a properly built rifle system is to shoot 30-50 cold bore/first shots of the day into a single group, and then 30-50 shots of a warm/hot barrel into a single group, then overlay and see the differences- as in the two 100 shot targets above.

I’m not trying to argue. I’m just trying to understand why what I’m seeing in these test results differs from what you’re saying.

You can argue as much as you want- constructive argumentation is required for learning. I appreciate it. The base differences seen here are inside the standard expected variation of these rifles and ammunition, and therefore can not be stated to be “different” due to barrel heat. There may be minute differences, but that can not be stated without further testing. And, those differences would not be usable/functional as we are limited by what we can adjust out and account for.

In order for there to be a “difference”, the difference must fall outside of normal distribution. That is, if a rifle system is constantly about a 1 MOA rifle- say 10x10 groups cold bore shots, the average was 1 moa, and the largest group was 1.3 MOA- but when fired 10 shots in a row (warm/hot barrel) the group was 2 moa. And then when a second 10 shot hot barrel group was fired it was 1.6 moa- then, yes you could say that the groups from that rifle open up when it gets hot. However, if the first hot barrel group was 1.2 moa, and the second was 1.3 moa: no, you could not say that the groups get larger when the barrel heats up- both are inside the true cone.

I’ve owned exactly one rifle out of many dozen in my life that most certainly was effected by heat. A Weatherby Vanguard 25-06. After a few shots if not allowed to thoroughly cool, it absolutely would spray bullets all over the place.

And that’s a thing. But it’s a bad barrel/improperly built/assembled rifle thing, not a barrels “walk” when hot thing. It points to a mechanic problem with the rifle system that should be addressed.



All of this is revolving around a best practices/optimized/functional/whatever way to zero and check zero, check group sizes, load development, load comparison, diagnose rifle/equipment problems, etc.
It’s not a rigorous white paper on “weather barrel mirage causes up to a .18683 MOA shift in apparent target location through a scope” thing. It’s a “to save time, money, energy, and get usable data- lay down, fire ten rounds, find the true center of all ten rounds (do not discount shots), adjust from that center, fire five to ten more shots, if needed make a small adjustment: you are now zeroed. If the ten round groups are too large for you, change bullet or powder- small changes won’t make large differences” thing.

 

[JGRaider]

Form said.... “the only shot that matters is the cold bore, and the first shot always lands into the same spot”. It’s simply not true. These statements are made by and large by people that do not have anywhere near sufficient data to come to that conclusion.

My personal experience says otherwise, but whatever. Most will buy that line of thinking hook, line, and sinker though. For hunting purposes there is nothing more important than that first cold bore shot, and 50+ years of hunting has proven it, at least to me.

 

[ResearchinStuff]

pics or it didn't happen. i've never seen Form make that claim, and it's easily disproven by anyone with a scoped rifle and 2 shells.

 

[Formidilosus]

Form said.... “the only shot that matters is the cold bore, and the first shot always lands into the same spot”. It’s simply not true. These statements are made by and large by people that do not have anywhere near sufficient data to come to that conclusion.

My personal experience says otherwise, but whatever. Most will buy that line of thinking hook, line, and sinker though. For hunting purposes there is nothing more important than that first cold bore shot, and 50+ years of hunting has proven it, at least to me.

What are you trying to say? What “ my personal experience says otherwise” are you referring to?

 

[JGRaider]

That you said this.....the only shot that matters is the cold bore, and the first shot always lands into the same spot”. It’s simply not true. These statements are made by and large by people that do not have anywhere near sufficient data to come to that conclusion

And my experience has proven otherwise.

 

[Formidilosus]

That you said this.....the only shot that matters is the cold bore, and the first shot always lands into the same spot”. It’s simply not true. These statements are made by and large by people that do not have anywhere near sufficient data to come to that conclusion

And my experience has proven otherwise.

What experience of data or tests have you done that show that the cold bore shot always does land in the same place?

To be clear- you have multiple rifles that produce 10-30 shot overlaid groups that shoot caliber size “groups”? (The “same spot”).

 

[JGRaider]

I don't recall you ever being there when I shoot and verify. They land under MOA in my rifles and have been doing that since 1981 when I started reloading and seriously hunting. If they don't I work up a new load that will. Hundreds of animals later is a good testimony as well.

 

[atmat]

I don't recall you ever being there when I shoot and verify. They land under MOA in my rifles and have been doing that since 1981 when I started reloading and seriously hunting. If they don't I work up a new load that will. Hundreds of animals later is a good testimony as well.

You can appeal to your experience as a random internet-er, or you can show objective data with others present.

@Formidilosus chose the second. You have perhaps unsurprisingly chose the first — and it’s why people are laughing at you.

 

[Formidilosus]

I don't recall you ever being there when I shoot and verify. They land under MOA in my rifles and have been doing that since 1981 when I started reloading and seriously hunting. If they don't I work up a new load that will. Hundreds of animals later is a good testimony as well.

Again what is your point?

If they land under MOA cold, they will land under MOA hot.

 

[JGRaider]

Here's 7 cold bore shots.........

 

[atmat]

Here's 7 cold bore shots.........

View attachment 604211

Hey, unrelated… but do you also happen to have a 60 year old 270 and own a canyon?

 

[JGRaider]

Here's 5 more cold bore shots atmat.....guess I better haul asss to the range and shoot a bunch of 10 round hot bore shots to prove it up. 270's are gay.

 

[Formidilosus]

Here's 7 cold bore shots.........

View attachment 604211

I understand you are trolling, however it is sad that you just go to fallacies to argue a point that won’t stand up to any actual analysis.

“I’ve killed deer so I am right, but I don’t clearly state what I am disagreeing with”.

 

[NSI]

Against my better instincts, I'm going to attempt to mediate here - solely because JGR is a WKR.

JGR: The claim proferred by the OP is that whether 10 shots are hot or cold, they will land in the same cone of fire as long as the system is "good."

It would appear that you are a proficient shooter with a good system. So it is no surprise to me or anyone else that you have killed many animals. The OP is simply stating that there is no need to allow the rifle to cool between shots, within reason.

Your positions do not appear to be in opposition. If you wouldn't mind, I've gotten a lot out of the dissection of the data presented in the OP and I'd love to see the thread return to an analysis of that and related data.

With best intentions,
-J

 

[JGRaider]

Thanks for the excellent post jourdan, and you make a solid point. I am definitely not in opposition to someone shooting 10 round rapid fire groups. I could care less. My point the whole time is that I find it to be a waste of time and not worth the effort, and my personal experiences validate it FOR ME. I could care less what someone else does with his load development, etc.

To say cold bore shots won't give you a solid indication of what your load/rifle/optic is doing is hogwash though, IMO.

 

[Diced]

Here's 7 cold bore shots.........

View attachment 604211

How wide is the lower right one on the stone? That thing is insane.