cold bore ???

[RustyRick]

I understand that a barrel heats up with each shot. I understand that steel expands with heat. I understand that the first shot might be else where than the next 5. On a hunting rifle that would not be too good in extreme situations.

(maybe I should invent a barrel heater) lightbulb

I'd like to read some scientific (or nearly so) technical paper on the effects and results around the "Cold Bore" issue.

I see opinions that one "MUST" know or test your "COLD BORE" results.

 

[J E Custom]

I understand that a barrel heats up with each shot. I understand that steel expands with heat. I understand that the first shot might be else where than the next 5. On a hunting rifle that would not be too good in extreme situations.

(maybe I should invent a barrel heater) lightbulb

I'd like to read some scientific (or nearly so) technical paper on the effects and results around the "Cold Bore" issue.

I see opinions that one "MUST" know or test your "COLD BORE" results.

Opinions are about all you will get because there is no one thing that is considered a cold bore except a cold bore. (Barrel is at the ambient temperature)

A cold bore can be cold and fouled, cold and clean, cold and oily, cold and dirty (with dust and dirt)
and ETC. and all will/can have an effect on accuracy or a POI shift. as the temperature of a barrel rises, there are many things that can effect the POI, Poor or no bedding, poor smithing where nothing is square or on centers, barrel is not concentric to the bore, contact with the stock and many more things can effect the poi as the barrel heats up.

The trick is to know your barrel and deal with it. I have several rifles that the first shot (Cold Bore)
shoots high and left about 1/2 moa from the Zero. after that they shoot where zeroed. so I shoot one fouling shot, Pull a bore snake through it and it is ready to go hunting and is good for 4 or 5 accurate shots. This is caused by oil left in the bore after cleaning and dry patching will improve it a little but these rifles still need a fouling shot before going hunting. after this first shot the poi will not change until I clean it again.

I have other barrels that don't need this fouling shot, just dry patching.

For match shooting this is normally not an issue because you normally have one or two sighters before you start the record shots. (But it is a must to know so you wont use the first shot for a final zero)

The term "Cold Bore"normally means that the barrel is at ambient temperature no matter what condition it is in.

J E CUSTOM

 

[Frank in the Laurels]

JE is correct ! There's lots of versions of this but it all deals with one condition....where does your rifle hit when you shoot it under hunting conditions, that first shot after dragging it around over everything imaginable.... Myself, after what I think is my rifle sighted in, I take it home and clean it Buthches Bore shine and all the other oils, right before I hunt with it, or around the same temperature I'll head to the range and fire a shot, then I'll let it sit there for an hour to adjust to hunting temperature and conditions as best you can and then fire a shot and see where it hits, that'll usually tell you where your at, if it's about where you want it I'll black tape the barrel and not worry about it again...too be honest I've never seen any of mine that were all that far off that it would miss any big game animal's vital zone s it might be all to do about nothing !

 

[Gene]

I always sight in my rifles a few days before season begins, usually 3 - 10 shots. I do not clean the barrel until season ends and I put it away for another year - unless water or moisture gets in the bore. Then, cleaning is a must.

One of my competition rifles does not settle down until 7 or 8 shots has gone down the tube.

 

[tbrice23]

(maybe I should invent a barrel heater) lightbulb

Maybe you should invent a barrel cooler !
That way you could shoot a group of cold bore shots instead of a group of hot bore shots.

I use a mattress pump.


After my final zero with a cold bore , 3 to 5 shots may take 45 min in 30°, it will not be cleaned until the season ends.

 

[Grumulkin]

The trick is to know your barrel and deal with it. I have several rifles that the first shot (Cold Bore)
shoots high and left about 1/2 moa from the Zero. after that they shoot where zeroed. so I shoot one fouling shot, Pull a bore snake through it and it is ready to go hunting and is good for 4 or 5 accurate shots. This is caused by oil left in the bore after cleaning and dry patching will improve it a little but these rifles still need a fouling shot before going hunting. after this first shot the poi will not change until I clean it again

Right. So your "cold bore" shot deviation is really caused by oil left in the bore and not because the barrel is cold. The phenomena with the first shots being wild after oiling the bore will be seen with pretty much any gun.

There is a way to avoid this. Don't leave oil in the bore after cleaning. Oil is NOT necessary to prevent rust. Really. In addition, since oil isn't compressable, if you have a very precisely made barrel, shooting through an oiled bore can/probably will deform the bore enough to be detected with an air gauge and the deformation will be permanent.

Prolix can be left in a bore followed by a dry patch to prevent rust and the first shots out of a bore so treated won't be wild. Microlon Gun Juice will also prevent rust but the technique is a little different; you don't run a dry patch through the bore after coating with Microlon.

You guys are also overthinking the hunting temperature thing. If your gun is so far off after a few shots that you can't hit a deer at 500 yards in the vitals, you need to get your gun fixed. Keep in mind that bench rest shooters shoot 5 shot strings over a few minutes and don't have shots wandering all over the place. In CMP matches 10 shots are put down range rapid fire.

 

[Mikecr]

I'd like to read some scientific (or nearly so) technical paper on the effects and results around the "Cold Bore" issue.

Wouldn't be worth the paper to you unless the testing involved YOUR shooting system(including reloading components, load, stock, action, scope & base/rings, barrel, and field rest). And this assumes normalized fouling(separate factor).

I see opinions that one "MUST" know or test your "COLD BORE" results.

Do you suspect this as untrue?

 

[Wedgy]

BarrelCool

If you don't want to carry the mattress pump around these work pretty well.

 

[FEENIX]

Barrel cooler is naturally provided when hunting in Montana. gun)

 

[J E Custom]

Right. So your "cold bore" shot deviation is really caused by oil left in the bore and not because the barrel is cold. The phenomena with the first shots being wild after oiling the bore will be seen with pretty much any gun.

There is a way to avoid this. Don't leave oil in the bore after cleaning. Oil is NOT necessary to prevent rust. Really. In addition, since oil isn't compressable, if you have a very precisely made barrel, shooting through an oiled bore can/probably will deform the bore enough to be detected with an air gauge and the deformation will be permanent.

Prolix can be left in a bore followed by a dry patch to prevent rust and the first shots out of a bore so treated won't be wild. Microlon Gun Juice will also prevent rust but the technique is a little different; you don't run a dry patch through the bore after coating with Microlon.

You guys are also overthinking the hunting temperature thing. If your gun is so far off after a few shots that you can't hit a deer at 500 yards in the vitals, you need to get your gun fixed. Keep in mind that bench rest shooters shoot 5 shot strings over a few minutes and don't have shots wandering all over the place. In CMP matches 10 shots are put down range rapid fire.

I agree in part, but all barrels will rust (Stainless or Chrome moly) after cleaning, I run a lightly oiled
patch through the bore to protect it until the next time I get ready to shoot it. I always dry patch, but you cant get all of the oil out of the bore. Only firing will remove any oil, solvent or preservative
completely Hence the reason for a fouling shot on some barrels. Other barrels don't seem to need this first shot, but I want to know if it is necessary on any of my rifles.

Most long range shooters/hunters want to stay within 1/2moa as far as the rifle will shoot . and any good custom barrel will normally do this.

As far as the number of shots before the rifle goes completely bad, Most good barrels will shoot there best for the first 5 to 7 shots, then they will settle in and remain on target with good accuracy
for as many as you want to shoot. Some matches are as many shots as possible in 50 Seconds and the average shooter could get 35 to 40 shots in 50 seconds. the rifles get very hot and even start smelling
. The accuracy stilled remained well under 1 MOA even though it was no longer as accurate and it was for the first 8 to 10 shots.

Basically, it is a personal decision and each person gets to decide what they want and how important it is.

Just my opinion

J E CUSTOM

 

[Grumulkin]

I agree that it's improtant to know how an individual gun shoots. I also know that stainless steel can rust. I know that, as you described, if oil is left in a bore the first few shots will be wild and thus the need for fouling shots. Since I quit oiling bores I have had no rust issues and the problem of first wild shots has vanished.

When I went to South Africa to hunt, one of the professional hunters observed that when clients came over, their guns shot high when checked on the range. I can see it now, the guns cleaned and the bores oiled in preparation for the safari. Gues what, I didn't have that problem.

The problem of shooting through an oiled precision bore and permanently deforming it was mentioned by none other than Kenny Jarrett at a Safari Club International convention.

 

[bigngreen]

I simply won't accept a rifle for hunting that has a cold bore shot that is not in the grouping ability of the rifle. I've seen a number of reasons for that cold bore shot syndrome, I've had an action that was just enough out of square that the barrel tenon would settle that first round. Many times it's bedding especially on heavy recoiling rifles with loosely bedded recoil lugs so it torques the action on that first round then it will over time move back. Oiled or clean bores just don't get it for long range hunting for me unless you've worked with the rifle enough to know what condition to leave it in to keep the cold bore in check, also bullet coating like HBN can level of this cold bore shot.
Most often it's cold shooter not cold bore, not shooting enough through the year or hunting season is an issue as well. I try to shoot a few hundred rounds of my hunting load with my rifle set up just as it is during hunting season with the same brass prior to season, I like to have 100 rounds loaded at one single time ready for hunting the week before season then I finalize my ballistics on that lot, every day I hunt I find at least one good long range target and put one round on it, this keeps my muscle memory and my system locked in so I can manage that first round with consistency and if I have to fill a second tag or send a second round I don't have to think about it being different than the first. I will burn a hundred rounds in a hunting season but I've only needed one round per tag for a lot of years on a lot of game!

 

[Barrelnut]

I simply won't accept a rifle for hunting that has a cold bore shot that is not in the grouping ability of the rifle. I've seen a number of reasons for that cold bore shot syndrome, I've had an action that was just enough out of square that the barrel tenon would settle that first round. Many times it's bedding especially on heavy recoiling rifles with loosely bedded recoil lugs so it torques the action on that first round then it will over time move back. Oiled or clean bores just don't get it for long range hunting for me unless you've worked with the rifle enough to know what condition to leave it in to keep the cold bore in check, also bullet coating like HBN can level of this cold bore shot.
Most often it's cold shooter not cold bore, not shooting enough through the year or hunting season is an issue as well. I try to shoot a few hundred rounds of my hunting load with my rifle set up just as it is during hunting season with the same brass prior to season, I like to have 100 rounds loaded at one single time ready for hunting the week before season then I finalize my ballistics on that lot, every day I hunt I find at least one good long range target and put one round on it, this keeps my muscle memory and my system locked in so I can manage that first round with consistency and if I have to fill a second tag or send a second round I don't have to think about it being different than the first. I will burn a hundred rounds in a hunting season but I've only needed one round per tag for a lot of years on a lot of game!

That's da ticket!

 

[Mikecr]

Grumulkin is right about residue of petroleum products remaining in the bore. This has to be burned out with a number of shots before fouling is stable. I get around this with an alcohol wash & dry pre-fouling as the last step of my cleaning.
I don't agree with generalizations that bore temps don't matter. With many barrel/cartridge/load combinations it does matter. Objective testing would show it matters.

Comparisons with competitive results are not useful in that the formats provide for preheating and prefouling (sighters) of bores prior to record shooting. There, it's stable temps and stable fouling, and with a measuring of precision(rather than accuracy), much less cold bore accuracy.

Actual cold bore load development takes a lot of work & time.