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

[donrleonard]

Go test it. Shoot a 10 round string and number every shot. Let your barrel cool between each shot. Then repeat it without cooling. It’ll give you a pretty good idea of how, if at all, barrel heat is affecting your group.

FWIW I’ve had two lightweight rifles with pencil barrels that will rattle out a 10 round group with no ill effects. One is a 6.5 and the other was a .280 Remington.

Great idea. Challenge accepted!

 

[wind gypsy]

It's a great point, and one that I need to drill on for hunting--staying in the scope, spotting impacts, and being prepared to take follow-up shots.

The thing that puzzles me is just how consistent it is. Two tight shots low, two high, and a random 5th shot inside of a 2" cone.

Do they progress in the same direction?

Other shooting gurus, like Joseph von Benedikt and Cliff Gray, do commonly see accuracy open up after as few as two or as many as 5-7 shots. Given their vast experience, I can't help but wonder if there isn't some systematic variance in the 1-10 shot range inside these 30-shot strings that Form reported here.

Not familiar with the Cliff Gray fella. I’m guessing they get a bunch of production guns that wear barrels that are not adequately stress relieved, carbon barrels that walk, etc so I’m sure it happens to a degree and I’m sure sometimes it’s not heat that is causing the issue as well but that’s what everyone is conditioned to assume.

 

[Macintosh]

The thing that puzzles me is just how consistent it is. Two tight shots low, two high, and a random 5th shot inside of a 2" cone.

I am a little skeptical if its legit to call this “consistent”. If you did 10 separate 5-shot groups, all staying in the gun for the full 5-shots, and every group progressively “moved” the same way (ie 2 on poa, 2 higher, then a third even higher) Id say the stringing was consistent. But I see in the 3 examples you posted the 5th shot in one case is high, and in the other case it’s 180-degrees in the other direction, and in one case a tight pair is more offset horizontally than it is vertically. I may have missed it, but how many 5-shot groups had the consistency you are referring to?

It just seems odd that if its walking UP as it heats as you indicated, that the 5th shot would be up in one case, and then below the first shots in the other case (all the stringing Ive ever seen with older rifle or those not floated, etc stays in one direction), and that the pair in the one case would be offset horizontally. Im no expert but regardless of whether its heat or something else that does not point to a consistent shift to me.

 

[nephewjephew]

The thing that puzzles me is just how consistent it is. Two tight shots low, two high, and a random 5th shot inside of a 2" cone.

I've chased my tail on a few guns like this. Not getting good (or confusing) 3 or 5 rd groups, chasing zero etc,etc. Shoot a 30rd group, I bet they all fall in the cone of the rifle. Once I started down this road I have had no problems (along with a scope that works). Its a great way to set a base line for the rifle and gives unbelievable confidence in the rifle system. More data to start with the better.

 

[donrleonard]

I've chased my tail on a few guns like this. Not getting good (or confusing) 3 or 5 rd groups, chasing zero etc,etc. Shoot a 30rd group, I bet they all fall in the cone of the rifle. Once I started down this road I have had no problems (along with a scope that works). Its a great way to set a base line for the rifle and gives unbelievable confidence in the rifle system. More data to start with the better.

I’m a big fan of more data. If the quality of shots are evenly distributed across a shot string, 30 shots is actually the magic number in statistics where the average (or central tendency) becomes meaningful.

Two reactions to this approach:

1. This is definitely the way I would do it if I was going to war (against varmints or humans). But as hunters we (and maybe/maybe not our rifle bores) are shooting cold for the decisive shot. This would be immaterial if the cone that a 30-shots string produces was indeed distributed as a cone. But in fact, many rifles in Form’s test demonstrated a clear elevation or windage bias to their “error” or drift. Some strings lined up vertically, some horizontally. That’s not a random cone. That is meaningful, non-random variation.

2. Until we have the shot-by-shot data, it’s still difficult to see whether accuracy opens up as more shots cycle through the weapon. As several others have pointed out, I still need to test more. And sadly I’m not the ideal candidate to be testing given my skill level (and pocket book!) But it appears to me that my rifle is more accurate in smaller shot strings (.5 moa for two shots, 1moa for 4, 1.5 moa for 5+). At least, that’s the hypothesis I have to test with more data.

I’ve got more ammo arriving today. Hope to get back to the range this week. Will follow up.

 

[nephewjephew]

If the quality of shots are evenly distributed across a shot string

Its more of a random numbers game. Say you have a gun that shoots 2 moa, and your zero is actually zero, as long as they all fall in that circle that's all that matters. The idea is not to get caught up in two were touching and the third was an inch high. Or 5 were in all an inch form each other and the next two were low. As long as they all fall in the cone of what that rifle can produce with that ammo. And a good way to figure that out is shoot a large group (30 seems to be the number). If you're worried about you barrel heating up, let it cool between shots. For shits and giggles try a 10rd group one hot one not, I was surprised in 3 different guns that it didn't matter at all (minus mirage).

This is definitely the way I would do it if I was going to war (against varmints or humans). But as hunters we (and maybe/maybe not our rifle bores) are shooting cold for the decisive shot

Who cares about going to war, don't you want to know what your gun can or can't do? Once you figure out what the gun is capable of spend the rest of its life shooting one shot groups for your "shooting cold for the decisive shot".

Once I decided to try this out for myself it instantly made sense. I had a clear picture of what to expect from the gun and the ammo. I could stop worrying about shooting groups and now I focus on shooting form field positions and getting comfortable at distance. Don't get over think it.

 

[E.Shell]

One thing to keep in mind when seeing a lot of vertical is that fatigue and shoulder pressure play into impact points, not just having a solid rest front and rear.

I often noticed students that initially shot well will begin to suffer vertical issues and high misses as the afternoon wore on and they accumulated fatigue. Their shoulder 'softens' and variations in shoulder pressure can be directly linked to vertical stringing

 

[Formidilosus]

I’m a big fan of more data. If the quality of shots are evenly distributed across a shot string, 30 shots is actually the magic number in statistics where the average (or central tendency) becomes meaningful.

Two reactions to this approach:

1. This is definitely the way I would do it if I was going to war (against varmints or humans). But as hunters we (and maybe/maybe not our rifle bores) are shooting cold for the decisive shot. This would be immaterial if the cone that a 30-shots string produces was indeed distributed as a cone.

They are distributed as a cone. 10 shots are not “data”. There is one gun that seemed to have shifted from hot to cold, so 3x10 round groups were fired.


This is a cone.

But in fact, many rifles in Form’s test demonstrated a clear elevation or windage bias to their “error” or drift. Some strings lined up vertically, some horizontally. That’s not a random cone. That is meaningful, non-random variation.

No, they didn’t. All you are seeing is random changes due to small sample sizes. When overlaid they just form a general cone.

2. Until we have the shot-by-shot data, it’s still difficult to see whether accuracy opens up as more shots cycle through the weapon.

Not correct. Each shot is a random event. You are trying to read tea leaves. Your vertical stringing is not barrel heat. And you do not have enough information to even say it even is stringing vertical.

As several others have pointed out, I still need to test more. And sadly I’m not the ideal candidate to be testing given my skill level (and pocket book!) But it appears to me that my rifle is more accurate in smaller shot strings (.5 moa for two shots, 1moa for 4, 1.5 moa for 5+). At least, that’s the hypothesis I have to test with more data.

Of course it is “more accurate” in smaller strings- that’s how groups work. You can just shoot two shots and claim it’s a quarter MOA rifle if you like?

 

[Macintosh]

...
1. This is definitely the way I would do it if I was going to war (against varmints or humans). But as hunters we (and maybe/maybe not our rifle bores) are shooting cold for the decisive shot. This would be immaterial if the cone that a 30-shots string produces was indeed distributed as a cone. But in fact, many rifles in Form’s test demonstrated a clear elevation or windage bias to their “error” or drift. Some strings lined up vertically, some horizontally. That’s not a random cone. That is meaningful, non-random variation.
...

I went back and re-looked at the targets. I'm not seeing the linear stringing, or even a "clear elevation or windage bias" you are referring to. If you are seeing something I'm not, maybe re-post the specific examples you're referring to. All I'm seeing is that all those groups are within the same cone, but the fringe of several groups has a shot or three that is outside the hot core...but in any 10-round group you will almost always see that--that's simply the "fringe" 5% or so of shots that fall more than 2 standard deviations or more from the zero, and the 27% that fall outside 1 sd from the zero…except in a 10-round group you would expect to only see less than 3 of these, so it frequently looks a little linear...keep shooting and you'll see it's not usually linear.

20 and 30-round groups are not for "going to war". 20 and 30-round groups simply show you the cone that you can bank-on for any random single first shot. Perhaps to prove this to yourself you need to shoot a 30-round group all at the same target, all without coming off the gun so re-building your position doesnt affect the group, and just let the barrel cool between shots...with 2 minutes between shots that's 1 hour of your time, and you'd have a sense of the true cone of your gun so in the future you know if what you are seeing in smaller groups represents a change.

 

[kthomas]

"cold bore shift" always seemed more like a "cold shooter" error to me.

Otherwise, it doesn't make sense. If your POI has a thermal variability to it, you will see it through all shots, not just your very first shot compared to all the other shots. That makes no sense.

Mind you, improperly stress relieved barrels will exhibit a walking POI with thermal variance. But that's a different issue than the so-called "cold bore shift".

 

[JGRaider]

I've never experienced this "cold bore shift " phenomenon. Never experienced this 30 rd group phenomenon either.

 

[donrleonard]

Thanks for the thoughtful replies, all. Here are my results from a return trip to the range yesterday. I would greatly appreciate it if you could help me interpret what I'm seeing here. In a follow up message I will try to respond to other comments--including what I saw in Form et al.'s original data.

Here's the TL;DR: My rifle/shooter/ammo combo appears to be more accurate when shooting five 3-shot strings than it is when shooting one 15-shot string. But in reality, my cold- and hot-bore shooting produced a similar MOA of around 2.5. This might be because I was breaking position between my cold bore shot-strings. Or it may be because I am an inexperienced shooter. Either way, none of this matters because my rifle is clearly more accurate than I am from actual field positions.


Setup:

It was 71 degrees yesterday, with a light (2-3mph) wind quartering from behind me. On the bench, the barrel of my Browning X-Bolt in 7PRC was exposed to the late afternoon sun. I was shooting with front and rear sand bags.

I was shooting at 100 yards so as to be able to estimate MOA accuracy the lazy way.

I could only afford to allocate 30 rounds for this test, 15 cold bore and 15 hot. A better test would involve more shots/datapoints. But these Barnes LR 160gr boxes ain't cheap, and I needed to spend at least 10 shots firing off of my bipod getting dialed in for next weekend's hunt. (More on that below).


Cold Bore 5 x 3-shot strings: 1 MOA, but with significant POI shift between strings.

The shot sequence for this cold bore test was to put 3 rounds on a 100 yard target in the top right corner, wait 10 minutes for the barrel to cool, then put 3 into the top left, then wait another 10 minutes, then 3 bottom right, then 10 minutes, then 3 bottom left, then 10 minutes, then 3 center.

Perhaps crucially, between each 3-shot string I broke shooting position and went over to the pistol range to shoot my Glock 20 to give the barrel 10 minutes to cool.

I found that after 3 shots the X-Bolt's sporter contoured, fluted barrel was on the verge of being too hot to touch and starting to mirage, but that after 10 minutes it was only slightly warm and giving off no mirage.

Here are the overall results, followed by my shot notes:



Top right (.75 MOA): First shot .5 inch low and left, next two shots .5 inch high-left and touching.
Top left (0.6 MOA): Three shots touching, half-inch low and right.
Bottom right (1.8 MOA): First and third shots right .75 inch, (pulled?) second shot 1.5 inches right
Bottom left (1.0 MOA): First shot low and left .75inch. Second and third shot touching high and right .5 inches.
Center (1.0 MOA): First shot inch high/right. Second and third shots touching 1 inch high. Stayed “in it” all three shots.

Average across five 3-shot groups: 1.03 MOA. Though it is interesting that the POI drifted. If I was to super-impose these five shot strings on top of one-another, we'd probably see an MOA of around 2.5.

While these results may appear similar to the 5-shot group results I posted a few days ago, these shot patterns are actually different. In those early ones, I was getting a tight grouping for shots 1 and 2, then another tight grouping for shots 3 and 4, then a wandering 5th shot.

In all but one of the shot strings yesterday, the very first and truest "cold bore" shot appears to be wandering. The following two shots--call them "warm-bore"--were touching. This pattern was followed for all but the bottom-right shot string, where the first and third shots fell next to each other. I felt like I pulled that second shot, and almost fired a 4th shot to prove it. But I didn't want to change the methodology, as it might be mistaken for post-hoc rationalization and could look like I was trying to confirm my bias.

As you'll see below, the beginning of my hot-bore shot string followed this 1-off, 2-on pattern as well.


Hot Bore 15 shot string: 2.5 MOA, with more variation along windage than elevation.

My shooting notes indicate that the first, second, and third shots (cool bore) were half an inch high and left, and again the second and third shots were touching. From there, the next dozen rounds began following the first shots into the paper half an inch above the bullseye, achieving about 1.5 MOA except for a couple of shots that went wide, giving me an overall result of 2.5 MOA.



Here, as with several of Form et al's rifles, I note that the hot bore shots show a pretty clear bias along one of the axes--in this case horizontal deviation. While the vertical shot dispersion yielded an accuracy radius of about 1.5 MOA, the horizontal shot dispersion pushed me out to 2.5 MOA.

Pouring so much lead (copper, actually) into one aiming point definitely convinced me that I needed to adjust my zero (down 2 clicks). The curious thing is that the half-inch-high pattern was not what I observed across all the earlier, cold-bore shots. Had I decided to zero off of those 15 rounds fired in five 3-shot groups, I probably would've left my POI alone and not adjusted my zero. If I was operating based on the theory of cold-bore zeroing, that's exactly what I would do.

Instead, I chose to adjust my zero down based on the hot-bore groupings on the bet that Form et al. are correct. Either way, I think there are two plausible, non-exclusive explanations for the more consistent grouping observed during the hot-bore test.

First, I wasn't breaking position between shots for the hot-bore test, other than coming out of the scope to reload. This is the variable that @wind gypsy alerted me to.

Second, as an inexperienced shooter it is possible that I was shooting cold in those first 15 shots. Once properly warmed up, maybe I was grouping more consistently.

But, for this shooter at least, none of the fretting I've been doing about hot-versus cold bore really matters a lick at this stage of my hunting journey because...


Epilogue: I suck at building a stable shooting position in the field.

I mentioned earlier that I saved the last 10 rounds from my two boxes to do some off-bench shooting from a kneeling position on my Spartan Precision bipod with 40 inch legs. This is the most common shooting position for me in the tall grasses of the West Virginia highlands where I hunt.

This was my first 3-shot string. All the same shooting parameters as before, but now from kneeling on a bipod.


The MOA for this shot string is infinity because 1 shot missed the paper entirely


The second and third 3-shot strings faired a bit better as I settled in. But still, pretty embarrassing results.



Here I was able to get all 6 shots on the paper. But I'm shooting at about 4 MOA from what should be a fairly decent field position (rifle fore-end stabilized on a bipod). That's "minute of deer" out to about 200 yards, which works for me in West Virginia. But it tells me that I have a lot of work to do before I head west to live out my Steve Rinella fantasies one of these years.


My big takeaways

First and foremost, my rifle is far more accurate than I am from field positions. Becoming better at establishing stable shooting positions in the field would be an infinitely more productive use of my time and energy than worrying about whether my rifle is sub-MOA when fired cold bore.

In terms of the cold vs hot bore tests, there are still too many variables in play for me to make any decisive conclusions.

Because I broke shooting positions between each of the shots in the cold-bore test, did that cause my POI to drift around the zero? I use a pretty hefty Spartan Classic bipod mount in place of my swing swivel stud. Perhaps varying fore-end flex caused by varying the position of the rifle on the front sandbag caused varying pressure on my otherwise free-floated barrel? Browning's polymer stocks are better than most, I am told, but they're not as good as non-polymer options.

The implication of this is not trivial. It would suggest that I have a 1 MOA rifle/shooter/ammo combination that is susceptible to POI drift depending on shooter/rifle positioning.

Alternatively, I think you could look at these drifting POI results and say "duh. Over 15 shots you are shooting a 2.5" cone at 100 yards. Your shooter/rifle/ammo combo is a 2.5 MOA combo. It just looked more systematic in these 3-shot groups because you were pointing at different corners of the target."

I am amenable to this argument. I think it is the one Form would make. But my hesitation is that the patterning in these cold bore shots appears to be SO consistent. Two shots touching, one errant shot, all inside 1.5"

There are probably other interpretations as well. This Lil-Rockslider welcomes feedback from the learned ones here.

Either way, I know that at this stage in my shooting career I need to focus my attention on building better shooting positions in the field. I didn't have my pack with me at the range yesterday. Maybe using it as a "rear bag" when firing from a kneeling position is the ticket. I am also considering switching to a tripod setup. Either way, I have some marksmanship fundamentals to work on.

Thanks for reading along. Again, I welcome all advice and perspective.

 

[Formidilosus]

Here's the TL;DR: My rifle/shooter/ammo combo appears to be more accurate when shooting five 3-shot strings than it is when shooting one 15-shot string. But in reality, my cold- and hot-bore shooting produced a similar MOA of around 2.5.

You have a 2.5’ish MOA system.

This might be because I was breaking position between my cold bore shot-strings. Or it may be because I am an inexperienced shooter. Either way, none of this matters because my rifle is clearly more accurate than I am from actual field positions.

That is good that you recognize what is going to cause misses in the field (it isn’t base precision for you).

Cold Bore 5 x 3-shot strings: 1 MOA, but with significant POI shift between strings.

The shot sequence for this cold bore test was to put 3 rounds on a 100 yard target in the top right corner, wait 10 minutes for the barrel to cool, then put 3 into the top left, then wait another 10 minutes, then 3 bottom right, then 10 minutes, then 3 bottom left, then 10 minutes, then 3 center.

Perhaps crucially, between each 3-shot string I broke shooting position and went over to the pistol range to shoot my Glock 20 to give the barrel 10 minutes to cool.

I found that after 3 shots the X-Bolt's sporter contoured, fluted barrel was on the verge of being too hot to touch and starting to mirage, but that after 10 minutes it was only slightly warm and giving off no mirage.

Here are the overall results, followed by my shot notes:

View attachment 779305

This is not “significant POI shifts between strings”. It’s just random variation that shows in all cones. You have clusters- high, low, left, and right. Aka- a cone.

Average across five 3-shot groups: 1.03 MOA. Though it is interesting that the POI drifted. If I was to super-impose these five shot strings on top of one-another, we'd probably see an MOA of around 2.5.

This right here should show you why saying “my rifle shoots X size” is nonsense from one, or even a few 3 or 5 shot “groups”.

The only thing that can be stated, is with that system and a bench, you have a high probability of hitting a 2.5 MOA target if the rifle is zeroed.

While these results may appear similar to the 5-shot group results I posted a few days ago, these shot patterns are actually different. In those early ones, I was getting a tight grouping for shots 1 and 2, then another tight grouping for shots 3 and 4, then a wandering 5th shot.

In all but one of the shot strings yesterday, the very first and truest "cold bore" shot appears to be wandering. The following two shots--call them "warm-bore"--were touching. This pattern was followed for all but the bottom-right shot string, where the first and third shots fell next to each other. I felt like I pulled that second shot, and almost fired a 4th shot to prove it. But I didn't want to change the methodology, as it might be mistaken for post-hoc rationalization and could look like I was trying to confirm my bias.

As you'll see below, the beginning of my hot-bore shot string followed this 1-off, 2-on pattern as well.

You are trying to read tea leaves. The only pattern is that like most other things, events tend to cluster closer together, then jump, then cluster, then jump. The rifle doesn’t know if it is the 1st shot or the 2nd.

Hot Bore 15 shot string: 2.5 MOA, with more variation along windage than elevation.

My shooting notes indicate that the first, second, and third shots (cool bore) were half an inch high and left, and again the second and third shots were touching. From there, the next dozen rounds began following the first shots into the paper half an inch above the bullseye, achieving about 1.5 MOA except for a couple of shots that went wide, giving me an overall result of 2.5 MOA.

View attachment 779325

As before, a 2.5 MOA system.

Here, as with several of Form et al's rifles, I note that the hot bore shots show a pretty clear bias along one of the axes--in this case horizontal deviation. While the vertical shot dispersion yielded an accuracy radius of about 1.5 MOA, the horizontal shot dispersion pushed me out to 2.5 MOA.

Horizontal stringing is common because a stable rest makes left to right input on the rifle by the shooter easier than up and down.

Pouring so much lead (copper, actually) into one aiming point definitely convinced me that I needed to adjust my zero (down 2 clicks). The curious thing is that the half-inch-high pattern was not what I observed across all the earlier, cold-bore shots. Had I decided to zero off of those 15 rounds fired in five 3-shot groups, I probably would've left my POI alone and not adjusted my zero. If I was operating based on the theory of cold-bore zeroing, that's exactly what I would do.

Instead, I chose to adjust my zero down based on the hot-bore groupings on the bet that Form et al. are correct. Either way, I think there are two plausible, non-exclusive explanations for the more consistent grouping observed during the hot-bore test.
First, I wasn't breaking position between shots for the hot-bore test, other than coming out of the scope to reload. This is the variable that @wind gypsy alerted me to.

Second, as an inexperienced shooter it is possible that I was shooting cold in those first 15 shots. Once properly warmed up, maybe I was grouping more consistently.

These are your first 15 shots overlaid quickly. You are a tick high to center, and it forms a general cone.




Here’s all 30 shots overlaid. There is no “pattern” to first shots. Draw a circle around all 30 shots and if you kept shooting, that circle would fill in.

But, for this shooter at least, none of the fretting I've been doing about hot-versus cold bore really matters a lick at this stage of my hunting journey because...



Epilogue: I suck at building a stable shooting position in the field.

That is the most important information that you gathered, save maybe the zero.

I mentioned earlier that I saved the last 10 rounds from my two boxes to do some off-bench shooting from a kneeling position on my Spartan Precision bipod with 40 inch legs. This is the most common shooting position for me in the tall grasses of the West Virginia highlands where I hunt.


This was my first 3-shot string. All the same shooting parameters as before, but now from kneeling on a bipod.

View attachment 779358
The MOA for this shot string is infinity because 1 shot missed the paper entirely


The second and third 3-shot strings faired a bit better as I settled in. But still, pretty embarrassing results.

View attachment 779365

Here I was able to get all 6 shots on the paper. But I'm shooting at about 4 MOA from what should be a fairly decent field position (rifle fore-end stabilized on a bipod). That's "minute of deer" out to about 200 yards, which works for me in West Virginia. But it tells me that I have a lot of work to do before I head west to live out my Steve Rinella fantasies one of these years.


My big takeaways

First and foremost, my rifle is far more accurate than I am from field positions. Becoming better at establishing stable shooting positions in the field would be an infinitely more productive use of my time and energy than worrying about whether my rifle is sub-MOA when fired cold bore.

This is why hit rates in the field do not noticeably change from a true .5 MOA rifle to a 2 MOA rifle.

In terms of the cold vs hot bore tests, there are still too many variables in play for me to make any decisive conclusions.


Because I broke shooting positions between each of the shots in the cold-bore test, did that cause my POI to drift around the zero? I use a pretty hefty Spartan Classic bipod mount in place of my swing swivel stud. Perhaps varying fore-end flex caused by varying the position of the rifle on the front sandbag caused varying pressure on my otherwise free-floated barrel? Browning's polymer stocks are better than most, I am told, but they're not as good as non-polymer options.

The implication of this is not trivial. It would suggest that I have a 1 MOA rifle/shooter/ammo combination that is susceptible to POI drift depending on shooter/rifle positioning.

Alternatively, I think you could look at these drifting POI results and say "duh. Over 15 shots you are shooting a 2.5" cone at 100 yards. Your shooter/rifle/ammo combo is a 2.5 MOA combo. It just looked more systematic in these 3-shot groups because you were pointing at different corners of the target."

I am amenable to this argument. I think it is the one Form would make. But my hesitation is that the patterning in these cold bore shots appears to be SO consistent. Two shots touching, one errant shot, all inside 1.5"

You do not have a 1 MOA rifle. You have a 2.6’ish MOA rifle, and there is no pattern to your 3 shot groups.

 

[Macintosh]

Form beat me to it, but since I made a pretty picture I’ll post it anyway.

This is the first 15 shots overlaid into one group (on the center target). It looks remarkably similar to the one Form posted.

 

[jaredg]

@Formidilosus
Form, to take this 30 round cone info and use it to establish the rifles "true zero" within the cone..... How do you do this this? Assuming you are not using ballistic software, do you measure the extreme edges for width and height and then divide by two, or do you throw out the outliers and focus on where the tightest 26-27 round group?

Forgive me if this has been asked / answered in another post and sorry if my question is not stated or worded correctly

 

[Seak_angler]

Great work as always. Great stuff guys

 

[Formidilosus]

@Formidilosus
Form, to take this 30 round cone info and use it to establish the rifles "true zero" within the cone..... How do you do this this? Assuming you are not using ballistic software, do you measure the extreme edges for width and height and then divide by two, or do you throw out the outliers and focus on where the tightest 26-27 round group?

Forgive me if this has been asked / answered in another post and sorry if my question is not stated or worded correctly

There are no “fliers”. Every shot is reality and must be accounted for. To do anything else is just mental masterbation to appease what you wished would have happened.


Draw a circle around all shots, then put an x in the very center- that’s what you zero off of.






Even if you make an oval, the center is less than a single click different.

 

[jaredg]

Got it, thank you

 

[ETtikka]

Tons of very interesting data; thanks to Form and others for this.

I am not sure if this has been asked before but for hunting purposes , would multiple 3 shot cold bore groups be more useful for establishing a zero vs one large hot bore group?

 

[NSI]

Tons of very interesting data; thanks to Form and others for this.

I am not sure if this has been asked before but for hunting purposes , would multiple 3 shot cold bore groups be more useful for establishing a zero vs one large hot bore group?

First, find out if your system holds a decent cone for 10 rounds. If it does, no need to do anything else.

If it doesn’t, ask yourself if you’re really ok with that. Assuming you have to be ok with it for some reason, (perhaps budget), then shoot small groups at the same point of aim until you land at statistically significant data. Overlaying is useless and simply creates a false sense of capability by viewing slices of the cone separately. See the last salvo of posts here.

Now, look at this single spaced group. Are you happy with the cone? If you are, you can zero off that and hunt to the best of your abilities, until budget or time allow for replacement of the system with one capable of holding a reasonable cone for a greater number of rounds.

Are you not happy with the spaced cone either? Good riddance. Get yourself a system capable not only of interesting precision but (while you’re at it) precision across a 10 round string.

Hope this helps,
-J