Cold Barrel Shots

[Mikecr]

The ultimate killer of 'accurate barrel life' is bore constriction due to carbon.
You may have noticed that carbon takes a set with time.
The longer you leave it, the tougher it is to remove. Copper is bad, but I don't like leaving carbon in a bore.
So when I'm done with any range session, or a week or two of hunting, I clean the bore to white metal.

Then there is the matter of storage and petroleum products left in a bore. IMO, there is nothing 'good' in this.
A stable layer of powder fouling cannot establish itself without first burning out what petro you left in there.
I've seen testing in the past(a long time ago) concluding that it took 6-8shts to clear standard Hoppes suggested cleaning.
If the bore is stored upward, the oil can migrate down into the chamber, action,, potentially the bedding.
What I do to remove these issues is dry pre-fouling as a couple steps in my cleaning routine.
With this, my 1st shot is as true as any to follow.

 

[danj]

How do you dry pre-foul ?

 

[Radman]

Just curious. If a rifle does indeed need a fouling shot to resume accuracy, what would stop a person from not cleaning the bore after a session at the range and then when hunting, use the rifle without being cleaned. Taking into count of course that the rifle hadn't reached the degree of fouling as to have excess copper fouling. Kind of makes sense to me to not clean a bore until copper fouling dictated that you clean. I'd like to see what others think about that!

I personally think that you are on the right track. I have always advocated that you can zero a hunting rifle, (first/coldshot accuracy), or you can zero a target rifle, (fouled/warm barrel accuracy). At least in my experience I have found this to be true. I personally think that it's more of a clean vs copper/lead fouled barrel issue more than a cold vs hot barrel comparison. JMO Without looking up the coefficient of thermal expansion of stainless steel versus carbon steel in MY experience stainless seems to walk more than steel. Again - as long as your rifle is zeroed for its intended purpose even this factor does not matter. I have owned several stainless barreled rifles, (got one now), & love 'em. I just know that with every single one of them the point of impact seems to shift more with the stainless as it warms. Again, if your hunting rifle is zeroed for the cold shot then this isn't an issue. Just my thoughts.

 

[Mikecr]

How do you dry pre-foul ?

After cleaning, I sloppy wash the bore with the best alcohol on hand and let it dry out.
Then I run a dry bore mop, which is saturated with dry tungsten disulfide (WS2), in with short stroking and eventual full stroke to burnish it into the surface. The alcohol can take an hour to dry, but the pre-fouling takes only a minute.

WS2 seems a universal fouling, in that it somehow matches every powder fouling (that's important).
It does not affect MV, and it cleans out same as carbon. With these attributes it resolves every single issue with moly.

 

[ShtrRdy]

After cleaning, I sloppy wash the bore with the best alcohol on hand and let it dry out.
Then I run a dry bore mop, which is saturated with dry tungsten disulfide (WS2), in with short stroking and eventual full stroke to burnish it into the surface. The alcohol can take an hour to dry, but the pre-fouling takes only a minute.

WS2 seems a universal fouling, in that it somehow matches every powder fouling (that's important).
It does not affect MV, and it cleans out same as carbon. With these attributes it resolves every single issue with moly.

Will this final treatment prevent corrosion?

 

[DDWing]

It's not the cold bore. It's the time of day you fire the shot in relation to the angle of the sun. Fire one shot every hour for 12 hours at the same spot on the same target and see what happens.

Thats a new one on me, because my rifles seem to hold the same poi no matter what time of day I shoot. What is the difference supposed to be? Because I don't see any.

 

[Barrelnut]

Thats a new one on me, because my rifles seem to hold the same poi no matter what time of day I shoot. What is the difference supposed to be? Because I don't see any.

See details in post #5. The issue is light refraction and the greater the angle of the light reflected from the target and the density of the air that the light is traveling through, the greater the difference is. This is actually a known issue in surveying and has to be accounted for due to things like the curvature of the earth. It's the same effect as mirage only more subtle.
It is the effect you see when aiming at fish while bowfishing. You don't aim at the fish, if you do you'll miss, because the light reflected from the fish to your eye is bent by the difference of the density of the water, compared to the air. The greater the angle of the light source to the fish magnifies the effect. This is true for most things you see at distance. Nothing is ever exactly where your eye and brain perceive it to be.

 

[DDWing]

See details in post #5. the issue is light refraction and the greater the angle of the light reflected from the target and the density of the air that the light is traveling through, the greater the difference is. This is actually a known issue in surveying and has to be accounted for due to things like the curvature of the earth. It;'s the same effect as mirage only more subtle.

But I still don't see any difference in poi. My shots hit the same no matter the time of day.

 

[Barrelnut]

But I still don't see any difference in poi. My shots hit the same no matter the time of day.

Great.

 

[dartem]

It's not the cold bore. It's the time of day you fire the shot in relation to the angle of the sun. Fire one shot every hour for 12 hours at the same spot on the same target and see what happens.

Don't think this applies to shooting with a scope.
Iron sights are a different matter. This is why you smoke your sights before a match. Thereby minimizing the effect of a changing angle of light on the sights...

 

[Teri Anne]

In the one shot every hour for 12 hours one has to take into effect that it's not only the lighting that will change. Wind will vary, temperatures will vary, barometric pressure will vary, temp of the so called cold bore will vary as will the temperature of the individual cartridges being fired. Yes, the brightness or darkness of the day with light changing accordingly will affect the point of impact unless the shooter makes allowances for that change, which an experienced shooter will do for all of the variables. Based on my experience the two variables that will make the most difference is heat and wind. Heat can change the muzzle velocity out of a cold barrel. Depending upon what you read changes in temperature can change the muzzle velocity between 1.5 fps to 1.7 fps per degree of temperature change. At one point the Army said that for each 10 degrees of temperature change the muzzle velocity would vary up to 100 fps, which is probably a bit extreme for today's modern ammunition. One thing that I have actually observed is hunters zeroing their rifles prior to the hunting season. It's a nice warm fall day on the range, temperature comfortably in the mid to high 70's. As an example where I am today in Wisconsin the high temp is forecast to be 79 degrees. If I zero my rifle today, then take it out into the woods in November for the deer season the temperatures will be, let's say for example 20 degrees means a difference of 59 degrees. a 59 degree difference will mean (using 1.5 fps for each degree of temp change) around an 88.5 fps decrease in muzzle velocity. Add that to the now cold soaked rifle and barrel (remember things shrink as they get colder) where the action is not as securely held in the action due to shrinkage and the scope mounts not gripping quite as well as they did at 79 degrees and that is why a lot of hunters end up shooting below the target and incredulously watch the deer of a lifetime bound away unscathed. The variables change with each and every shot, and no two shots are ever quite the same, even when shooting 10 rounds in a 60 second time limit during competition. The big variable here is the temperature of the barrel/action which increases with each shot and that is why it's important to have a rifle that barrel temperature does not adversely affect it's zero.

 

[Mikecr]

Will this final treatment prevent corrosion?

I haven't engaged in destructive testing for cause/prevention.
All I can suggest is that I haven't had corrosion with coated bores or bullets, with indoor storage and moderate condition field use.

 

[LaHunter]

See details in post #5. The issue is light refraction and the greater the angle of the light reflected from the target and the density of the air that the light is traveling through, the greater the difference is. This is actually a known issue in surveying and has to be accounted for due to things like the curvature of the earth. It's the same effect as mirage only more subtle.
It is the effect you see when aiming at fish while bowfishing. You don't aim at the fish, if you do you'll miss, because the light reflected from the fish to your eye is bent by the difference of the density of the water, compared to the air. The greater the angle of the light source to the fish magnifies the effect. This is true for most things you see at distance. Nothing is ever exactly where your eye and brain perceive it to be.

I recall someone posted a time lapse video, maybe on this forum, with a spotter on a tripod that had a reticle centered on a target. I don't recall if the distance to the target was mentioned. As the sun moved across the sky, the scope's reticle 'appeared' to move on the target. That video really illustrates well what you are describing.

 

[Teri Anne]

Nobody ever said that shadows did not move with changes in the angle of the sun, While a video of this sort shows shifting due to different angles, the all important shooter who would make changes to correct for this was missing. It's easy to prove the shift. Just simply put a stick, the longer the better in the ground and mark the movement of it's shadow on the ground. How do you counteract this shift? You simply move with the shadow.