Cold bore vs Warm Bore

[TassieTiger]

What’s the biggest separation someone has witnessed between 1st cold bore shot and then the next - warm barrel shot - asking as for a hunting purpose.
I witnessed a friend with his 6.5 cold bore shoot at a target that was almost 1.5 inches awAy from the general poi once warm...I thought that would be okay for a deer but for head shooting rabbits...?
So what’s the biggest discrepancies seen ?

[in2anity]

What’s the gun? I have seen it in a Ruger American before. Problem seemed to go away with time, that and I filled the forend with fiberglass and free floated more with a socket+sand paper. But I do still think it inherently improved as the barrel broke in.

That’s also presuming the barrel is free floated... a tightly fitted forend is not conducive to shooting tiny groups.

[TassieTiger]

This is a sako in a thumb hole stock, stainless barrel with After market fluting.

What is in the real of normal?

[Wm.Traynor]

Tassie Tiger,
How well did it shoot before the fluting? Reason I ask is, if it wasn't stress relieved after the work, stresses could have been induced which cause the point-of-impact difference, between cold and warm shots.

[marksman]

l have seen several inches with some but the normal l see with match grade barrels is 1/2 an inch at most
l have seen as normal for some factory barrels to take a few shots to settle down before the rifle will truly group shots together

in the photo below it shows sighting targets #1 being 22 dasher with first cold bore shot out to the right then 4 shots, the middle target #2 shows the first cold bore shot off the the right from my 6mm dasher using 105gr bergers the 4 shots, and the 3rd right hand target shows my 6mm dasher shot straight after using 100gr sierras with no flyer or cold bore shot and shooting a nice tight group to roughly the same point of impact as the bergers

[TassieTiger]

Tassie Tiger,
How well did it shoot before the fluting? Reason I ask is, if it wasn't stress relieved after the work, stresses could have been induced which cause the point-of-impact difference, between cold and warm shots.

Not sure mate - I think it was purchased already done. It prompts the question for my friend though - sight it in to cold bore or hold over or...

[TassieTiger]

Very interesting MM - if that 6mm was a hunter - how would you sight in ? I guess if deer was on the board, you could prob sight in as needed, but bunnies...sight for warm...or hold over.

[in2anity]

Man that sucks it’s a sako - you’d think the likelihood of a lemon would be slim.

Very interesting point by WM - the thought that immediately popped into my head was also barrel tensions. A cheap Ruger barrel you’d expect might be a bit of a gamble - you buy one, you roll the die. But not a sako - unlucky. Then again, secondary fluting may have a profound impact on barrel tensions.

In any case, check the bedding and the free floating, make sure there’s nothing funky going on there.

[TassieTiger]

Man that sucks it’s a sako - you’d think the likelihood of a lemon would be slim.

Very interesting point by WM - the thought that immediately popped into my head was also barrel tensions. A cheap Ruger barrel you’d expect might be a bit of a gamble - you buy one, you roll the die. But not a sako - unlucky. Then again, secondary fluting may have a profound impact on barrel tensions.

In any case, check the bedding and the free floating, make sure there’s nothing funky going on there.

Thing is - once warm / fouled, it’s typical sako...very bloody accurate.

[in2anity]

Thing is - once warm / fouled, it’s typical sako...very bloody accurate.

So if it’s fouled, then left to fully cool, does the problem still exist? Also do you know how new the barrel is?

[marksman]

Very interesting MM - if that 6mm was a hunter - how would you sight in ? I guess if deer was on the board, you could prob sight in as needed, but bunnies...sight for warm...or hold over.

it is a hunter Tassie, its what l have been dropping the fallow with at distance
all my rifles are hunters if not they are for looking at

with regards to fluted barrels, Gale Mcmillan said he would not warranty any of his barrels that someone had fluted for that reason (stress) and that the metal between the flutes would not be as strong as where it was not fluted causing bad vibrations, who knows
l dont own any barrels that are fluted

[TassieTiger]

[
So if it’s fouled, then left to fully cool, does the problem still exist? Also do you know how new the barrel is?

I’ve only ever witnessed my friend target shooting - but, when we leave it between sets, the issue returns each and every time at about 50/70% of the original “walk” - then, bang, next shots are incredible. I don’t know much more about it, I know he has had it for a long long time but it was second hand when he acquired it - it was just an interesting point I was thinking about. He said it’s by far his worst cold / warm shooter and I guess it’s in line with what MM posted for his 6mm,

Thing is - the 1.5 inch walk at 100 is obviously more profound at distance so...I question that rifles ability as a first shot, hunting rifle (depending on quarry of course).

I wonder if there is worse ? I wonder why it occurs?

[Stix]

I have an uneducated theory that its something to do with the heat in the chamber/receiver shifting the alignment of the cartridge somehow/something to do with heat around the barrel/receiver junction anyway...

My T3 7-08 does it with a magneto strapped to the barrel....25"-.5" groups open up to .75"-1.0" groups respectively with the first cold shot flyer.
With magneto strapped on, can clearly see the flyer clocking around the group as the loads increase...
Thing is, take the magneto off & the groups open up to .75"-1.0", and the first cold shot flyer stays within the larger group....

I stopped wasting ammo on trying to figure it out....its not a 300 yd bunny headshooter, but it will hit a goat in the head at 200 easy, so i just have to deal with it as much as i hate it.

If its a hunting rig (as mine is)...set it up so the warm barrel group is on song & hold for they flyer.. ....my theory for that is with the first shot you often have the time to think about the hold-off...if however you need quick follow up shots-say running goats going nutso because you upset them with the first shot,--get a second shot into a deer while on the skiddadle,--smack a cat at 200 that is trying to Matrix move its way into the scrub,--you dont have the time nor mental space to think about the hold-off as well as any adjustment to lead your target, so better off letting your concentration funnel purely into instinct & let hand-eye coordination take over then & just rely on the reticle being true POI.

Ofcourse, that depends on what youre hunting/shooting, & how long between shots.

If its a varmint rig & youre only going to smack one bunny out to 300 at a time every 10 mins in the Tassy cold air, the cold shot may be the way to go for zero...

There is always the option of a Xmas tree reticle with hash marks for referencing the cold shot at given ranges on a set magnification...thats how i shoot the reduced loads in my little 204 that have a diff POI..

Anyway...thats be dun my thoughts rite there mister...

Oh & marksman...those targets...ppffftt...

[Strangedog]

My Win 94 30.30 prints them gradually higher every shot till after about 4 when its 3-4 inches higher than the first at 100m. I put it down to the barrel band. I'd like to know if others have this issue.

[in2anity]

My Win 94 30.30 prints them gradually higher every shot till after about 4 when its 3-4 inches higher than the first at 100m. I put it down to the barrel band. I'd like to know if others have this issue.

This is very typical of a lever gun. Partly the barrel band but also the tightly fitted timber forend to barrel contact.

As the barrel heats, it expands away from the timber yielding the vertical string you speak of. This can be mitigated by RTV silicone bedding the forend giving it some room to “breath” so to speak.

If interested, more info can be found in this article I wrote surrounding the subject: viewtopic.php?f=2&t=11991

[Madang185]

Suggest that it is a matter of fouling rather than heat, foul all of my barrels particularly before attempting to shoot groups. Usually one shot is enough but I have found barrels that prefer two.

[marksman]

this shows the effects of fouling the barrel on my 30-06 viewtopic.php?f=2&t=10886
but after fouling it shoots till it is cleaned again and needs refouling

but if this is a consistent thing meaning you need to fire a shot before the rifle will group its not fouling it looks more like barrel stress IMO

other things eg... poor bedding or improper fit of barrel would not give any consistency at all

[in2anity]

When your shoot your sighters during a comp, the second is much more telling than the first

[straightshooter]

Most common cause, although it is not the only one, is failure to substantially remove oil and or other fluids from barrel prior to the first shot.
Thinking that it may be due to barrel warming is a misconception. If that were to be the case then there would be equal further warming with subsequent shots with similar movement in the point of impact until there is equilibrium between the rate of warming and the rate of cooling.

[Stix]

Then what are the other causes straightshooter...?

Because i dont oil my barrel every group & negate to remove it all before shooting again.

Also why is it that you assume some equilibrium isnt reached after one shot...?

[straightshooter]

Then what are the other causes straightshooter...?

Some of these may be....
Shooter settling down after first shot and improving trigger control.
Shooter settling down after first shot and not flinching as much.
Anything on the rifle that can move under recoil doing so on the first shot and staying there for subsequent shots until the rifle is repositioned.
For example bedding, scope mount, scope internals.

Because i dont oil my barrel every group & negate to remove it all before shooting again.

I don't understand what you are trying to say. You might care to elaborate.

Also why is it that you assume some equilibrium isnt reached after one shot...?

Each shot contributes heat to the barrel. So the temperature at any given point in the barrel would have to rise exponentially with each subsequent shot unless the barrel is allowed to completely cool to ambient temperature prior to the next shot.
For temperature equilibrium to exist after the first shot you would have to believe that each subsequent shot contributed no net heat to the barrel. For that to be the case then the first shot couldn't have contributed any net heat to the barrel as well.
That would be inconsistent with Newton's law of cooling.

[SCJ429]

I don't agree that the first shot landing outside the normal group is due to oil or other fluids remaining in the barrel. It could be caused by this but if you have patched the barrel with clean dry tight patches it is most likely not the cause.

I think for myself, when shooting at the bench, it is not due to the rifle settling or me flinching.

I find that my rifles shoot low for the first shot with a clean barrel. I put this down to lower pressure being produced. Since there is no carbon in the barrel which would usually fill the edges of the lands, I think that the lack of carbon is changing the position of this shot. If I clean my rifle mid comp for carbon, I find the first shot is also low but subsequent shots are back inside the group. I find that when shooting between groups, especially during winter, the barrel has cooled but the first shot is still inside the group.

I try to fire a fouling shot out of my hunting rifle before I go into the paddock if possible to make sure the bullet goes where I intended.

Many people have experienced unbedded rifles where the group walks up the target as the barrel gets hotter and hotter. This may be why they think the cold bore shot is low.

[Blr243]

I like to hear all your ideas , People disagreeing with each other is totally cool. Eventually we all gain a lot of extra knowledge and come out the end well informed

[Stix]

I don't understand what you are trying to say. You might care to elaborate.

I was referring to your earlier suggestion that first shot flyers are most often due to oil left in the barrel.
Whereas my rifle shoots first shot flyer every cold shot...as is i believe the issue of the OP...&we dont oil the barrel between groups.

Each shot contributes heat to the barrel. So the temperature at any given point in the barrel would have to rise exponentially with each subsequent shot unless the barrel is allowed to completely cool to ambient temperature prior to the next shot.
For temperature equilibrium to exist after the first shot you would have to believe that each subsequent shot contributed no net heat to the barrel. For that to be the case then the first shot couldn't have contributed any net heat to the barrel as well.
That would be inconsistent with Newton's law of cooling.

All i was suggesting in my previous comment to this reply of yours, was that surely its possible for the occasional rifle to reach an equilbrium after just one shot & settle there for a few shots, before excess heat causes another POI shoft.
I dont think this is likely in most cases--logic would say its something to do with the barreled action/stock touching or as marksman said pressure on it...
Maybe a combo of both heat...
Anyway, im not suggesting youre wrong, im just brainstorming...because sometimes this reloading caper causes a storm in the brain...

[Ziege]

Biggest difference I saw was with a Remington 783, cold bore shot on the money, as soon as any heat was added to the mix the stock turned to melted cheese and not another shot was landed

[Grandadbushy]

Who's to say the first cold bore shot is the one that is out it could be the other shots there after ,I get a tiny bit of walk with my 22-250 nothing to worry about .
I always set my zero on the first cold shot because if your hunting or pest shooting it's usually the only one you'll get ,but if you do get another shot it won't be that far from the first . If you're getting major walk or stringing or any other movement and can't problem solve it yourself then get someone who is capable to do it . Some problems are thin barrel , scope mounts loose, faulty ammo, damaged crown, needs glass floating, loose screws, copper fouling , dying barrel , and so on there is a numerous amount of things you just have to work your way through them and hope you get it fixed early but if you can't well then it could well be the rifle is a dud either way I would have to know or it would drive me mad, but never loose heart mate

[wildcard6]

I've often used the expression 'cold bore shot', but what I really mean is 'clean bore shot'. I used to do a lot of spotlighting and my routine was to ensure that the barrel was fouled before firing any kill shots. Over the course of a [cold] nights shooting, EVERY shot was what you could accurately call a cold-bore shot, and there was no inaccuracy caused due to temperature. It was only that 'fouler' that I considered important, so as to give all following bullets the same conditions in the barrel from there on out. In a good, free-floating barrel the variance between the clean bore and fouled barrel is only very small, but not all barrels are created equal, and some can show considerable variance in point-of-impact.