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

[T-Stick]

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Let's see some of your best groups. Pics man, show us what you're talking about.

I'll try to post some tomorrow

 

[ETtikka]

So if we take a known good rifle system and fire 30 rounds back to back and establish a cone of fire that Form often refers to, is the overall conclusion that 30 cold bore shots let’s say 30 days in a row would produce the same cone of fire?

In other words , Cp and Cpk would be the same and standard deviation of each group would be the same ??

 

[Jimbee]

I sort of did this with a .270. I had 10 circles drawn on a piece of cardboard. Ten separate days I shot 10 shots, 1 at each target without waiting between shots. So the first target was 10 cold bore shots and the tenth target was a pretty hot barrel. All the groups were the same size. It was a stainless tikka superlite. Try it and find out?

 

[The Guide]

So if we take a known good rifle system and fire 30 rounds back to back and establish a cone of fire that Form often refers to, is the overall conclusion that 30 cold bore shots let’s say 30 days in a row would produce the same cone of fire?

In other words , Cp and Cpk would be the same and standard deviation of each group would be the same ??

Your 30 day group would statistical all fall within your 30 shot cone of fire but not necessarily be the same as your 30 shot cone of fire.

Jay

 

[Strider]

Absolute pure Rokslide Gold!

 

[Macintosh]

So if we take a known good rifle system and fire 30 rounds back to back and establish a cone of fire that Form often refers to, is the overall conclusion that 30 cold bore shots let’s say 30 days in a row would produce the same cone of fire?

In other words , Cp and Cpk would be the same and standard deviation of each group would be the same ??

That is essentially the experiment this thread is about. The variable introduced is 30x breaking position. That is not insignificant by itself.

 

[Formidilosus]

So if we take a known good rifle system and fire 30 rounds back to back and establish a cone of fire that Form often refers to, is the overall conclusion that 30 cold bore shots let’s say 30 days in a row would produce the same cone of fire?

In other words , Cp and Cpk would be the same and standard deviation of each group would be the same ??

Functionally correct. In properly stress relieved barrels with no outside influence, the two groups would look very similar with the except of the inherent variation in 30 round groups. Increase the number to 100 cold bore shots, and the 100 “warm” or “hot” rounds will be inside the cold bore cone.

 

[ETtikka]

Functionally correct. In properly stress relieved barrels with no outside influence, the two groups would look very similar with the except of the inherent variation in 30 round groups. Increase the number to 100 cold bore shots, and the 100 “warm” or “hot” rounds will be inside the cold bore cone.

So the cold bore cone size would be larger than the warm bore cone size, for 100 rds?

 

[Dobermann]

So if we take a known good rifle system and fire 30 rounds back to back and establish a cone of fire that Form often refers to, is the overall conclusion that 30 cold bore shots let’s say 30 days in a row would produce the same cone of fire?

In other words , Cp and Cpk would be the same and standard deviation of each group would be the same ??

In addition to what Form said, for most shooters, the more likely variables here are mirage from the barrel heat for the 30-shot group vs variances due to cold shooter, different clothing, and positional inconsistency for the 30x1 shots - rather than what the barrel is doing.

 

[Marbles]

So the cold bore cone size would be larger than the warm bore cone size, for 100 rds?

No. By "inside" he means the same size, i.e. not spilling out of the cold bore cone.

 

[2-Stix]

T-Stick...ya been on the Rokslide 11 days...relax and let go. Deep breath...a lot will be changing in your future. ROAL Reaper, drop test, your groups are too small, Tikka, UM, 6mm, fishnets, shoot2hunt, tmk, eldm, heavy for caliber...did I miss anything fellas?

 

[Shraggs]

Meaningful practice with real world shooting positions. Practice should be hundreds if not thousands of rounds depending on distance snd terrain.

 

[chamois]

Here’s a take from applied ballistics just the other day. He is talking about variation between 5-round groups, and % of groups within 1sd, 2sd’s etc. in other words he is also talking about dispersal of shots falling into a bell curve when you look at the total dispersion.
View attachment 999573
View attachment 999574View attachment 999575

Thanks for sharing.
Statistical dispersion translates into different groups, different not just in their size, but in the center of their point of impact.
In other words you can neither adjust your scope by shooting a 3 shot group.

 

[atmat]

did I miss anything fellas?

Manscaping.

 

[T-Stick]

OK I was asked to share some of my targets. I didn't do my load development with the intent to post them on Rockslide so I don't have a spread of data sheets. About 5 years ago I threw away a mountain of targets because my rifles all had their loads and some for a few decades. Then about 3 years ago a friend invited me to go mule deer/coyote hunting in eastern Montana and indicated that they had a 1,000 yd range set up on their farm. So this got me started again on checking, tweaking and creating some longer range hunting loads.

I will start with posting some groups with my 243 that I checked/tweaked/ or developed for 300 yard targets. I started longer range woodchuck hunting for field practice and data with various loads testing for accuracy and bullet expansion. I'm also testing my shooting in various field positions. I select one load as a 00 elevation and 00 windage baseline. The other loads get shot at 300 and then I record the POI adjustments needed to switch bullets in the field without resighting in. During the course of this testing I installed a brake and then a suppressor.

So here goes with some groupings and kill shots for the 87 grain Hornady

Zero confirmation shots at 300 yds



Interestingly enough I killed two chucks at 300 yds from the same hole in about a week's time. I shot from my ATV from a bipod sitting that was sitting on a platform on my front rack using the handlebars to stabilize my arms.

Here is a pic of the shooting rig with my 223 pictured (not my 243)



From this rig with 243 (with a brake) are two first round kill shots at 300 yds





243 with a previously developed 100 grain Speer BTSP at 420 yds from a bog bipod (243 unbraked and unsuppressed). The chuck was sitting at its hole and I could only see the top of the shoulders and head above the hay. First round kill headshot. I was using a 400 yd ballistic dot and almost held too high but it was dead center hit and took off the top of his head.



Another load with a Berger at 300 yds



Another 300 yd load with an ELDX. The measured rounds are the group and then their is the scope adjustment shot to confirm POI with the ELDX load. As you will see I use my reactive targets over and over because I was not intending to post clean targets online.

 

[Choupique]

Theres no point in posting 3 round groups. The crowd here has learned that they are statistically meaningless. All rifles can produce a random act of accuracy and stack 3 bullets on top each other sometimes.

You might really have a 0.2 moa rifle and operator, but that isnt likely and you should expect pushback around here.

 

[BLJ]

Wolverines were great.

 

[T-Stick]

So one forum member asks me to post whatever I have knowing I don't have Rockslide standard data targets. The next member tells me my posts are meaningless. Point taken. I will note in the chucks' obituaries that they have all died statistically meaningless deaths.

 

[Billogna]

So one forum member asks me to post whatever I have knowing I don't have Rockslide standard data targets. The next member tells me my posts are meaningless. Point taken. I will note in the chucks' obituaries that they have all died statistically meaningless deaths.

I for one think it shows a lot of humility on your part to participate in an open and honest way, showing whatever you have to show. Most other people who have their beliefs challenged the way that you have, simply aren't that brave. And you're not the first one we've seen be put through that grinder!! lol Truth be told the pics of the groups don't tell us much, except that you're a pretty fair shooter and that you're willing to learn!

 

[Choupique]

Point taken. I will note in the chucks' obituaries that they have all died statistically meaningless deaths.

Don't do that. Keep an open mind about it. Shooting large (9+ round) groups really tell the story and most people here have gone through this progression themselves. What everyone has found out is that traditional shooting wisdom (Sub MOA all day, hot barrels shoot worse, if I do my part, flyers, etc) is basically all BS. It happens often. New guy shows up, same stuff posted as other new guys, and they either buy in and learn some stuff they didn't know before or they don't.

There's lots of guys popping LOTS of primers every year and sharing their data to the benefit of everyone. As in, 10,000+ shots a year.

A lot of it comes across as people being assholes. They aren't. They've just had the same discussions many times over and are trying to help people see the light.