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

[atmat]

“Hot" barrels and big game hunting don't mix.

I’m confused by this statement. Are you saying “hunting barrels aren’t shot enough during a hunt to heat up, so this is all pointless?” Or are you saying, “hunting barrels shouldn’t be heated up because that’s bad for their accuracy?” Sorry, legitimately just trying to understand.

 

[JGRaider]

I'm saying if you're having to kill big game animals with a smoking hot barrel, you've got an equipment problem. I've never shot more than 4 rounds at a big game animal in 52 years of chasing them.

 

[atmat]

I'm saying if you're having to kill big game animals with a smoking hot barrel, you've got an equipment problem. I've never shot more than 4 rounds at a big game animal in 52 years of chasing them.

Thanks for clarifying!

I would argue somewhat against that, as I’ve shot plenty of hogs in TX on 85 degree nights where it seems the barrel never wants to cool.

Also, even if you don’t think your barrel will ever get hot enough during big game hunting — it’s nice to know how it would perform if it did.

And although you could identify the true cone of your rifle with 30 “cold” shots, it’s nice to know you don’t have to take a full day to get that data by letting it cool each time.

Either way, if you’ve got a good system and are having no issues killing animals at your distances with your 5 round shots, by all means keep doing it. A lot of folks here are killing animals at very far ranges, and want to know exactly how true their barrel is.

 

[mt terry d]

Many thanks. So…the shoot2hunt podcast edpisode I listened to part of the other day “we suck at shooting”…who was the guy that insisted there was a shift between a 10-round zero and a “10 cold bore rounds-zero”? I assume he’ll either be eating crow on the podcast, or he has some other comments? Seems pretty crystal clear to me that there is no difference, but do you or he see any caveats? (No pencil-thin barrel tested, etc??)

When I heard Jake say "I believe..." I thought "Oh oh! That's like saying the word 'fl*er' to Form or waving a red flag in front of a bull ." Personally, I rather wave a red flag in front of a bull.

Great job guys.

 

[Marbles]

I specifically said "big game hunting" rifles.

I specifically read where you said big game originally, my reply specifically remains the same, so I will not repeat it.

 

[JGRaider]

Thanks for clarifying!

I would argue somewhat against that, as I’ve shot plenty of hogs in TX on 85 degree nights where it seems the barrel never wants to cool.

Also, even if you don’t think your barrel will ever get hot enough during big game hunting — it’s nice to know how it would perform if it did.

And although you could identify the true cone of your rifle with 30 “cold” shots, it’s nice to know you don’t have to take a full day to get that data by letting it cool each time.

Either way, if you’ve got a good system and are having no issues killing animals at your distances with your 5 round shots, by all means keep doing it. A lot of folks here are killing animals at very far ranges, and want to know exactly how true their barrel is.

Hogs do not equal "big game" IMO, and neither does any other vermin including prarie dogs. I've killed hundreds of hogs and 99% of the time I can easily get within 100 yards and at night, within 50. Once again, if you're equipment scatters rounds large enough to miss these targets then you have a big time equipment problem.

My point is exactly where you went with your last paragraph........a guy needs to be familiar enough with his quarry and equipment to know whether he needs to waste time with 10 shot groups, cleaning your barrel every 100 rounds, barrel break in, brass cleaning, and all the other stuff some people obsess with.

 

[atmat]

Hogs do not equal "big game" IMO, and neither does any other vermin including prarie dogs. I've killed hundreds of hogs and 99%

For sure. But my big game rifle is my hog rifle.

Once again, if you're equipment scatters rounds large enough to miss these targets then you have a big time equipment problem

I’d argue that’s the beauty of big groups: you know exactly how much the system will scatter.

But it sounds like we’re in agreement to know your system well.

 

[ElPollo]

Not sure why a guy should worry about hot bore shot groups for a big game rifle setup? I've been big game hunting since 1971 and never fired more than 4 consecutive shots at a game animal. Prarie dogs and vermin are another matter.

I think there is some important context you might be missing on this. Like others have said, the point is more about getting a more accurate zero that addresses error between the “normal” 3-5 shot groups. The need for that arises primarily in long range situations. If you are a sub-300 yard big game hunter, this likely does not apply to you because variation of an MOA or even two will still get you on the vitals. If you have to stretch that out a bit or deal with significant wind drift, then that sort of zero error becomes an issue.

I’ve had one barrel in my life that showed significant heat shift. It was a Savage 99 built in 1971. That gun could would start to shift on round 3. By round 7-8, the POI would climb 5” and shift 3” right at 50 yards. Not much you can do with a barrel like that.

 

[rileybassman]

Super cool test thanks Form!

Target 7 is interesting to me as it's probably what a lot of hunters run into which makes them think that a hot barrel opens up groups - how would you interpret the difference between the two? I suppose you already did interpret and said potentially ammo related, but cold to hot groups seemed to noticeably open up no?

I guess maybe a better question is that, I agree that center of POI seems close/within statistical variance, but the group seemed to "open up" - would you call this a by-product of heat, or just the statistical variance of that barrel?

Very cool test and really appreciate the tremendous amount of effort that went in to this!

 

[Formidilosus]

I guess maybe a better question is that, I agree that center of POI seems close/within statistical variance, but the group seemed to "open up" - would you call this a by-product of heat, or just the statistical variance of that barrel?

That’s just variance of groups with that ammo and barrel and is a near perfect example of group size variance with no changes- up to +/- 30% from “average” for ten round groups. The next two ten round groups I shot of that ammo from that gun and ammo were both right at 1.7 to 1.8 MOA when shot at the same speed and temperature, which is what it is averaging for that combo- the rifle simply doesn’t like that ammo.

That’sbthe rifle used for the Scope Field Evals, and is by far one of the most known rifles of them all.

The first start of this “test” was a few weeks ago just using 5 round groups. The top is 5x cold/first shot of the day. The bottom is after the rifle has been shot a bunch, absolutely smoking. Water sizzled when poured on it-




And the composite 10 rounds.

 

[rileybassman]

That’s just variance of groups with that ammo and barrel and is a near perfect example of group size variance with no changes- up to +/- 30% from “average” for ten round groups. The next two ten round groups I shot of that ammo from that gun and ammo were both right at 1.7 to 1.8 MOA when shot at the same speed and temperature, which is what it is averaging for that combo- the rifle simply doesn’t like that ammo.

That’sbthe rifle used for the Scope Field Evals, and is by far one of the most known rifles of them all.

The first start of this “test” was a few weeks ago just using 5 round groups. The top is 5x cold/first shot of the day. The bottom is after the rifle has been shot a bunch, absolutely smoking. Water sizzled when poured on it-

View attachment 600310


And the composite 10 rounds.
View attachment 600309

Super cool - love it thanks!

 

[magnum]

Great report and test procedure! Nice job!

This whole thread has me wondering about the origins of this “myth”. It’s been talked about for as long as I can remember. Over the years I’ve heard it talked about by people at all levels of shooting knowledge and competence. It certainly doesn’t find its origin on Rokslide forum. How did the idea of cold bore shift start and why did it become popularized?

 

[atmat]

Great report and test procedure! Nice job!

This whole thread has me wondering about the origins of this “myth”. It’s been talked about for as long as I can remember. Over the years I’ve heard it talked about by people at all levels of shooting knowledge and competence. It certainly doesn’t find its origin on Rokslide forum. How did the idea of cold bore shift start and why did it become popularized?

I don’t think it’s a “myth.” It’s a real thing for crummy barrels. Manufacturing hasn’t always been the standard it’s at now.

 

[rileybassman]

I don’t think it’s a “myth.” It’s a real thing for crummy barrels. Manufacturing hasn’t always been the standard it’s at now.

Well and poorly bedded/relieved stocks I would say come into play - the wood stocks that they, themselves warp or change with heat etc.

 

[Macintosh]

I specifically said "big game hunting" rifles. In 40 years of reloading, I've never not had 3-5 shot groups do the trick. Almost 400 big game animals and hundreds of hogs later, the stats and experience I've had don't lie. Killing what you're hunting isn't that hard.

If I want a 10 shot group, I'll shoot a couple of cold bore shots at the same target over a 5 day period. "Hot" barrels and big game hunting don't mix.

I've never experienced this cold bore shift either, and agree it's a myth, as is the mandatory 10 shot group. I've never had a proven 3 or 5 shot 200 yard group all of the sudden throw a flyer out into oblivion somewhere as some are led to believe.

I guess I'm not following, you said if you wanted a larger group you would shoot 2-round groups 5 days in a row, presumeably to avoid a hot barrel? If it's not to avoid a hot barrel, then why would you not simply shoot one group and be done?

As far as needing a larger group size, that topic has been beat into multiple-dead-horse submission, here and elsewhere. Are you saying your 3-round group center is identical to your 10-round group center, or are you saying the variation is irrelevant given the size of the targets and the ranges at which you hunt?
It's perhaps not relevant for most of my personal hunting since I rarely shoot critters past pretty darn close range, but I'm not sure how one could say its not relevant for "big game hunting" writ large? A 3-round zero that happens to land near one side of the cone of fire can still very realistically be 1/2" off from true center...1/2" off=3" of built-in error at 600 yards. Even in a 1moa gun that much error puts a solid % of even your perfectly placed shots completely off a deer-vital-size target, even before you start accounting for other factors. Given the existence of hunting at long range, that magnitude of easily-correctible error seems relevant. Even eliminating the shots outside the core of this group, there are plenty of 3-round groups that could randomly fall together that would put your zero significantly off from the actual average center. If so, how do you suggest people make certain that their 3-round zero isnt shots # 4, 5 and 21, which appear to be a full inch from true group center? (Or 1, 2, 3. Or 7, 8, 9. Or 17, 18, 19. etc). Do you see it differently?

 

[atmat]

Well and poorly bedded/relieved stocks I would say come into play - the wood stocks that they, themselves warp or change with heat etc.

In general, precision equipment was not what it is now.

 

[JGRaider]

I guess I'm not following, you said if you wanted a larger group you would shoot 2-round groups 5 days in a row, presumeably to avoid a hot barrel? If it's not to avoid a hot barrel, then why would you not simply shoot one group and be done?

As far as needing a larger group size, that topic has been beat into multiple-dead-horse submission, here and elsewhere. Are you saying your 3-round group center is identical to your 10-round group center, or are you saying the variation is irrelevant given the size of the targets and the ranges at which you hunt?
It's perhaps not relevant for most of my personal hunting since I rarely shoot critters past pretty darn close range, but I'm not sure how one could say its not relevant for "big game hunting" writ large? A 3-round zero that happens to land near one side of the cone of fire can still very realistically be 1/2" off from true center...1/2" off=3" of built-in error at 600 yards. Even in a 1moa gun that much error puts a solid % of even your perfectly placed shots completely off a deer-vital-size target, even before you start accounting for other factors. Given the existence of hunting at long range, that magnitude of easily-correctible error seems relevant. Even eliminating the shots outside the core of this group, there are plenty of 3-round groups that could randomly fall together that would put your zero significantly off from the actual average center. If so, how do you suggest people make certain that their 3-round zero isnt shots # 4, 5 and 21, which appear to be a full inch from true group center? (Or 1, 2, 3. Or 7, 8, 9. Or 17, 18, 19. etc). Do you see it differently?

View attachment 600385

That's not at all what I said. I said I think 10 shot groups at one sitting to be worthless for a big game hunting rifle. IF I were inclined to see what a 10 shot group looked like for a specific load/rifle, I would be more inclined to shoot either 1 cold bore shot over 10 different days at the same target, or maybe 5 different days of 2 shots. Even at that, I think 10 shot groups for big game hunting are a complete waste of time and ammo. Especially given the fact that 95%+ of all big game animals are killed under 300 yards.

 

[atmat]

IF I were inclined to see what a 10 shot group looked like for a specific load/rifle, I would be more inclined to shoot either 1 cold bore shot over 10 different days at the same target, or maybe 5 different days of 2 shots.

But why when this proves you don’t have to wait and shoot cold bore? It’s illogical to waste that much time.

 

[JGRaider]

Why? Because I have zero interest in sitting down and shooting a 10 shot group, because, once again, I never have and never will shoot 10 consecutive shots at a big game animal, ever. I will shoot 10 cold bore shots at different big game animals every single year. Why practice something you will never, ever do?

 

[amassi]

But why when this proves you don’t have to wait and shoot cold bore? It’s illogical to waste that much time.

Your yelling into the void as the kids say


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