deadidarren
Well-Known Member
The way I see it is they are not exactly the same therefore dissimilar
Why factory ammo still shoots pretty accurately after time and handloads seem to diminish accuracy over time
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SMDunn
Member
Blame the Zinc, copper and zinc are in different places in the galvanic series plus an alloy of zinc and copper (aka brass) is in yet another position. This may contribute to the problem if there is a good "electrical" connection between 2 of them. This is the process that makes sacrificial corrosion work in industrial applications (often involves and electrolyte/ solution though). Sorry if I am way off beam here or if I have made it even more confusing!
If it were a problem piping systems would have problems when they have water flowing through them. Brass valves and copper pipe and fittings are the industry standard and they have water with continuous flow unlike a bullet which could get wet it would not cause an issue unless submerged for a very long time. Not sure what that time would be but it would be years.
Blacktailer
Well-Known Member
I have noticed the same phenomena with year or 2 old reloads. I now only load what I am going to use for a particular hunt/season with a few extras. My theory is that the brass/bullet junction either develops some corrosion or weld if you want and either changes the internal ballistics similar to a bullet jammed into the lands or sticks at one point on the circumference of the bullet and causes it to enter the rifling crooked.
Nothing scientific but have seen a sub MOA rifle shoot 1 1/2-2 inch groups with older proven loads then go back to normal with fresh loads of the exact same components.
Also know others who have experienced this. YMMV
As far as why factory fodder doesn't do this, the factory could be using some sort of bullet lube since a lot of guys buy factory stuff and it could be years before they shoot up the box.
Nothing scientific but have seen a sub MOA rifle shoot 1 1/2-2 inch groups with older proven loads then go back to normal with fresh loads of the exact same components.
Also know others who have experienced this. YMMV
As far as why factory fodder doesn't do this, the factory could be using some sort of bullet lube since a lot of guys buy factory stuff and it could be years before they shoot up the box.
I would think possibly if there was moisture in the powder when you load in other words humidity in the stored powder or humidity when you loaded it would be possible over time that the powder is more saturated and this could cause issues. IMO the corrosion, weld, dissimilar metal theories are old wives tales. I don't understand how it is scientifically possible. If someone could show me data to prove this wrong I would stand corrected.
Please read this description.
Think about very clean new brass casses and bullets pressed into the case neck under pressure.
"The reason behind why cold welding can bond two metals together without heat is because of the removal of the oxide layers on the surfaces of the materials being joined.
Almost all metals in normal conditions have some type of oxide layer on them, even though it may not be visible to the naked eye. These metal oxides form a barrier that prevents the metal atoms on the materials from being pressed together and bonding with one another. However, once the oxide layer is removed, the metal atoms are able to join with one another with enough pressure.
To remove the oxide layer, various mechanical and chemical methods are used. Wire brushing, degreasing, and other techniques are used to ensure that the metals surface is free from oxides. The metals must also be somewhat ductile. Industrial machinery is then used to create the substantial amount of pressure needed to create the metallurgical bonds."
It seems that the necessary things are in place to create this process, at least to an extent.
It has also happened in the space program where two metals laying on one another in the vacuum of space bonded to each-other.
I do believe this is the cause, not corrosion, I have not seen a hint of that in the loads I have had this happen to.
David Tubb stated that he loads his match ammo seated long and finish seats them before use.
Think about very clean new brass casses and bullets pressed into the case neck under pressure.
"The reason behind why cold welding can bond two metals together without heat is because of the removal of the oxide layers on the surfaces of the materials being joined.
Almost all metals in normal conditions have some type of oxide layer on them, even though it may not be visible to the naked eye. These metal oxides form a barrier that prevents the metal atoms on the materials from being pressed together and bonding with one another. However, once the oxide layer is removed, the metal atoms are able to join with one another with enough pressure.
To remove the oxide layer, various mechanical and chemical methods are used. Wire brushing, degreasing, and other techniques are used to ensure that the metals surface is free from oxides. The metals must also be somewhat ductile. Industrial machinery is then used to create the substantial amount of pressure needed to create the metallurgical bonds."
It seems that the necessary things are in place to create this process, at least to an extent.
It has also happened in the space program where two metals laying on one another in the vacuum of space bonded to each-other.
I do believe this is the cause, not corrosion, I have not seen a hint of that in the loads I have had this happen to.
David Tubb stated that he loads his match ammo seated long and finish seats them before use.
That pressure at minimum appears to be about 45,000 psi up to 90,000 psi. I am still confused how cold welding can occur when seating a bullet in brass and also how that ties to a cold weld occurring due to handloaded ammunition sitting for a certain amount of time.
JiminAZ
Well-Known Member
If you think you have "cold welded" the bullet to the brass, take a suspect loaded cartridge and bump the bullet a few thou in a die.
If it moves it sure as heck isn't "welded". Maybe stuck, maybe bonded by electrolysis, but not welded.
If it moves it sure as heck isn't "welded". Maybe stuck, maybe bonded by electrolysis, but not welded.
I'm not saying these are "welded" as in a real cold welding machine! BUT, I have welded enough to know there are good and bad welds. Yes, good cold welding takes high pressure. How much pressure does it take to make a bullet stick? Perhaps the pressure / neck tension can do it. Most eeryone that has had this happen sayes it is happening with clean brass and new un-lubed bullets, and in a relatively short period of time. I believe Tubb said less than 2 months, I know mine was. I would think he knows how to avoid contamination and corrosion, I do. Clean copper and brass are perfect metals to cold weld! Makes sense to consider this as a probable cause.
med358-boise
Well-Known Member
I have expereinced the same change in accuracy so I now do as a previous poster suggested. I load up 20 for the hunt and load up another batch of 20 for the next year but leave them a caliber plus 30/100 long and put a note in the box to reset OAL before shooting. The following year, I will now have 6 rounds for confirming zero and 14 for the hunt.
I etiher use up any spare rounds for practice or if I end up with ammo from a couple of years back, I put them in a kinetic bullet puller give them a few gentles raps to ease the the bullet out a little and them put them into a box for re-seating.
I etiher use up any spare rounds for practice or if I end up with ammo from a couple of years back, I put them in a kinetic bullet puller give them a few gentles raps to ease the the bullet out a little and them put them into a box for re-seating.
Yes, that would stop cold weld.
Applying powdered graphite works well.
If reloading fired brass, not cleaning the carbon out of the neck stops cold weld. The two metal surfaces must be extremely clean for cold weld to take place.
