It is my understanding that this is more of a "cold shooter" problem rather than a phenomenon that some rifles experience. I can also see the possibility if the rifle had something loose, the bore had been cleaned, or if the barreled action had been taken out of the stock between shooting sessions. However, some swear that some rifles do have a first round shift in accuracy that they attribute to the "cold bore shot". I have heard this from some pretty seasoned shooters also which surprised me and prompted me to ask here. I have posted this question on other boards trying to get the best feedback.

Thoughts?

Being ARFCOM you are going to get both as the "definitive" answer.

Sad isn't it?

I'm by no means a super secret squirrel ninja sniper, but my experience has been that cold bore shots are more shooter than gun.  I've hit a lot of first shots, including numerous hunting trips where I didn't have time to shoot 30 rounds to warm up the gun before getting the kill shot.

To a large extent, it boils down to how good is the rifle and how good is the shooter.

If you have a rifle that shoots well enough (and you keep good enough notes) you can figure out what the rifle does with CB and CCB shots--and do it reliably. A rifle of this quality level needs to shoot under 1 MoA for the CB and CCB "errors" stand out of the "noise" pattern the gun typically prints. There are plenty of rifles good enough for the shooter to figure out where the CB and CCB shots land.

As to the cold shooter phenomenon, it comes down to whether the shooter gets his head together prior to the first shot going off. Body in a Natural Point of Aim position, Eye pupil in line with the scope, Rifle supported correctly, Breathing under control, Mental processes under control, trigger finger under control. I like to watch the target for a full minute on the first shot, reading the wind, reading how my body is allowing the gun to sway back and forth, observing the period of sway, making sure the eye is on line with the scope, making sure the parallax is set right, taking a few dry fires to see if the flinch is under control,... And then after watching all this, I consider taking the first moves towards actually firing the weapon--that is loading it.

clean bore/cold bore is my understanding

has nothing to do with the shooter, though I can see how it might

This.

Thanks for the replies. That pretty much lines up with my understanding of the subject. What I was trying to clear up is this is not so much a issue that caused by the temperature of the bore but more of a cold shooter or clean bore shot. I think the term cold bore shot misrepresents what is actually happening and for some is an excuse for flinching with that first round.

In my experience, this is more of a shooter issue.  I am with Rob when he spoke of doing 5-10 dry fires prior to taking first shot.  I dry fire the shit out of my rifles and haven't noticed any dramatic shift in my POI with my first shots out of cold bores. However, when I used to not dry fire just before actually firing, that first round would have behavior similar to a "flyer."  

On this topic, when I am dry firing, I always visualize the "boom" of the rifle and the subsequent recoil impulse.  As in many other disciplines (fighting, teaching, etc...) visualization is a great way to improve technique.

We just used the same cleaning method after every string of fire, so the fouling of a CCB was always consistent, but the difference between clean and just before cleaned was minimal, if that makes sense.




It makes sense and we were consistent with cleaning as well. The cleaning was at the end of the day or mission though. That didn't really affect the poi imo either. I can see that it would, if you never cleaned.

Same experience here.

 

It your rifles were always clean, how did you determine it was the temp of the barrel?  At what temperature did it start to group? Could you pre-heat your rifle and avoid this issue? If the change in temperature from one shot made that much difference, what kept the following shots together?

These are all serious questions.

Thanks.

I don't clean my rifles until accuracy deteriorates. With that said, regardless of whether or not it's cleaned, I notice a difference in that first round, which I attribute to barrel temperature.

Depending on the type of shooting I'm doing, I may or may not shoot a single round off target or at a secondary target, in order to bring the temps up a little. This allows all of the subsequent rounds to have a relatively closer barrel temperature when fired, assuming a consistant gap between shots for slight cooling.

My reasoning is, as many know barrel accuracy CAN possibly deteriorate with a hot barrel. So there most likely IS a connection with a change of accuracy on that first round from the barrel being colder.

HOWEVER. The change of accuracy with that shot IS predictable assuming you know your weapon inside and out and how it will react to conditions. If I am shooting either a factory or reloaded round that I frequently use and know very well how it performs in my rifle, I can predict where that cold bore round will go and adjust accordingly. For example my Larue Stealth I shoot for the MOA All Day challenge. I know that rifle. I know the rounds I put through it. I've shot it cold bored and warm. I can shoot it and know how the poi will shift depending on temperature.

What temperature do you notice a shift and does it go away when its warmer outside?

There's no exact temperature I can report as everyone will have different results depending upon barrel profile, ambient temp, etc...

If a single round can elevate barrel temperatures between 30-80 degrees (As a hypothetical average) then add that to the ambient barrel temp, which may vary depending on the day/weather. At that point you may have an estimated value as to where you need to start for consistant results.

Of course then you need to determine cool down time between shots in order to avoid over heating. Once you have all of that calculated, you'll have a range where you'll most probably see repeatable results or groups.

Again, if you know your weapon, you can work around this though.

That right there will be a huge factor. Barrels with different contours will heat differently.

I totally agree with the statement that things taught in the military don't always apply. I experienced that myself. However the fact remains true that with higher temperatures, barrel accuracy does suffer.

 
But the slight touch from a Houge stock will throw shots 3 inches? Do you see why we have a hard time seeing this?


 

OP. What ?

If you hunt. All first shots are cold bore, cold shooter. Unless you have some kind of crystal ball how in the fuck do you expect to quantify the change from round to round. How much temp change is too much ? While there may certainly be a sweet spot !
What are you going to do carry a digital temp gauge around and decide you can only fire within a certain range.. ? Retarted thinking.
how far you want to go with the BS... Barrel fouling, effect of temp on an un fired round in the chamber soaking up heat from the barrel that was hot, increased fouling at the crown, effect of heat mirage on sight picture, etc.

Stop over thinking shit you have little to no control over.

Well, there is a big difference between physically impacting the bbl and a +/-10deg change in bbl temperature.

 

I agree. It's not a drastic change at the lower temps. But there is a change in poi. However, as I had said the change is negligible and predictable if you know your weapon.

A crystal ball isn't required. If you know your weapon and the ammo you are using, the result will be very close to similar each time unless a round is out of spec in some way.

 
How much "physically impacting" does a stock do when free floated before loading of the bipod and then not after???

 
And they say I am the one fighting and being argumentative around here...

I'm not sure I understand what you're getting at.

 

I'm only talking about how crappy stocks will impact accuracy when the bbl makes contact with it. There is a difference between that, bbl harmonics, etc - and slight temperature changes.

 
it's from another thread around here...

I have a crappy Howa pencil bbl hunting rifle around here somewhere that will hold tight until about the 10th round before it gets hot enough to shift POI.

 


My work gun never seems to get hot enough to do that at all.




Even sitting in AL July heat all day out in the open.








The temperature was all of them on that particular day.


 

Depending on the barrel though, you will see a difference. You said it yourself "You would need a very thin barrel for that to happen."

So it is a possible phenominon, correct?

Totally with you on the comparison between factory barrel and hand lapped, as well as comparing the cleaned vs. dirty though.

If one round was enough to heat up your barrel to the point of shifting POI, how can you expect for the next 4 or so to stay in a group? The barrel temp will change with each shot, what's so important about the first one?

In all the rifles I own, MTU contour down to mountain rifles, I have never had a cold bore shift. I have produced a "cold shooter shot" many times but cannot make a rifle shoot out of the group strictly based on the first round through a cold barrel.

 
Mathecb, it doesn't matter... There are certain Tier 1 guys here that say one thing one day and totally something different the other day. They believe that just because they were once a secret squirrel sniper that those of us mere mortals just don't understand. How can we be as knowledgeable as they are? We are just civilian shooters that don't even know what end of the barrel the boolits come out of. They have all the facts and dam us all to hell when we speak out of turn.


 

I find it interesting that the military cleans their bolt rifles as much as they do.  I think it has become mundane knowledge that rifles are most accurate when filthy as shit, so I guess we'll disagree on that one too ;)

I am curious to know if the military has collected data on what happens with the first shots out of rifles that have not been cleaned but are cold?  I believe the clean bore is an issue more so than the cold bore only because I have seen a couple clean bores that have rather dramatic POI shifts their first several shots

Either way, I do this stuff for fun and it is something I will now be more cognizant to observe amongst myself and fellow shooters while out.  

Also, Recon, thank you for your service.

I don't know about the military, but I think the FBI did some comprehensive testing on this.

 

I was also under the impression it was as much about the clean bore as it was the temperature.


As Rob mentioned:

Bartlein Barrels interview.  They touch on cold bore starting at the 6 minute mark of the video.
https://www.youtube.com/watch?v=rW6SF-jlbkg

If you get into the science there may be some real cold bore change, but I haven't seen it unless it was shooter error.  I shoot around 3/4 moa average group size with my 223 and my cold bore shot always falls within that distance with both clean cold and fouled cold shots.  With my 260 I'm usually around 1/2 moa average group size when there isn't shooter error involved  That rifle also always puts the cold bore shot within the best group size I can typically expect to be able to shoot.

So while there may be some science to prove that there is a cold bore shift,  I would say the capability of the shooter/rifle combo is the bigger determining factor.

respectfully,
again, in most situations, the barrel will start a string of fire at the ambient temperature.   some days, that will be 30 degrees, some days 100 degrees.  nobody changes their ZERO based on temp, though of course everyone changes their long distance dope based on temp.
i have measured multiple barrels with a FLIR thermometer over a 10 round string, and posted the video in threads here.   They show on film, that the barrel increases temperature a little less than 12-13 degree  WITH EVERY SHOT.

in other words, after your cold bore, the second round will traverse a barrel roughly 12-13 degrees hotter.  for the 3rd round, the barrel will be 24-26 degrees hotter.   Etc.   For the 10th round, the barrel is still 12-13 degrees hotter than the 9th round.    (of course, the exact number 12-13 degrees would be dependent on the cartridge and particular powder and the mass of the barrel.  in my case, it was medium palma, 260rem and reloader 17.  so YMMV but i would expect a pretty similar number for most 308win based cartridges.)

the point is the physics says EVERY TIME you burn a bunch of powder  in the chamber, you're adding heat to the barrel.   The barrel doesn't go from "cold" to "hot" after 2-3 rounds.  It continues to get incrementally hotter with each round.

It would be practically impossible to to track dope for every barrel temperature so it is quite fortunate that barrel temperature seems to make absolutely no difference in a rifle with no bedding issues.

what changes is not just temperature, but fouling.  again, respectfully, if you start every day with a clean and cold bore, it seems like you would not be able to tell the difference, so i could see where the confusion might arise.  i'd suggest starting some days with a cold dirty bore and see how that works for you.  the reason we don't clean our barrels is so we do NOT have to work fouling into our dope.   i don't change my dope at all based on barrel condition.  i only change it based on environmentals (density alt)

i could be mistaken, as i often am, so please educate me if you disagree with the above.   i'm not trying to be argumentative.  i just don't think there is any evidence to support cold bore shifts in most match rifles.  pencil barreled factory hunting rifles with no bedding are a different story.

ReconB4,

Thanks for the response, I welcome all opinions and knowledge. I think we are talking about two different things here. I am assuming the bore has been fouled prior to the cold bore shot. The first round through a clean barrel will fly differently due to what it contacts in the barrel. The following shots experience very similar friction which causes the rifle to settle into zero. Again, I'm not talking about a clean cold bore shot,  that's different and I think we all can agree a POI shift is common and expected. However, I cannot see how a cold bore shot (dirty/fouled bore) could possibly fly differently based on barrel temp alone. Wouldn't your zero change with just the slightest change in temperature? Mine doesn't, and I don't own a rifle that puts a CB shot out of the group.........unless it was a CCB shot (Clean cold bore).

Thanks.

no need to apologize.  you certainly didn't come across as a jerk to me.  i didn't take it that way at all!.  
when somebody has a lot of experience that differs so much from mine, I want to know why.  i usually learn something.  i'm not poking at you, just trying to figure out why you see cold bore shifts and i don't.

One of the things that our instructor pressed into us was that we should always use the same number of strokes/passes when we cleaned. Since we could never truly clean the bore completely, we would settle for having a consistently fouled bore, which would be the equivalent of a clean bore shot for us.


Since we clean the rifle every 10-20 shots, the bore was more or less consistent, no matter what state it was in. (as it relates to a string of fire)




I'm not sure if I'm explaining that correctly, but you get the idea.


 

This made our CB/CB shots about the same as our 5th shot or 10th shot.

now that you're out, do you see the same thing in your personally owned rifles?

i meant shifts as large as 1.5" which i assume was at 100 yards.   that's pretty huge.

That's massive. I've never seen that.

 

@100?

 

That's really significant!


You know, I'd like to get a hold of a rifle with shifts like that because it would really help in narrowing down the culprit.