How long until cold welding occurs?
- Thread starter fatelvis
- Start date
Not sure if there's an exact answer to this. I've had some, but not all, from the same box with a 1989 loading date on the label. Since I started reseating older loads about .010" before use, there have been some older handloads by around a year or so where all is fine. Some not. Nothing newer has given that CA-RACK sound when reseating. Maybe something changed in my process?
Very unscientific, I know, but around '89 or 90 seems to be about the time I started using Imperial dry neck lube, but cant be sure. Memory is hazy & nothing in my notes. Maybe when I stopped using the tumbler?
Very unscientific, I know, but around '89 or 90 seems to be about the time I started using Imperial dry neck lube, but cant be sure. Memory is hazy & nothing in my notes. Maybe when I stopped using the tumbler?
I’m not a believer.
The best answer is . . . it depends.
The biggest factor is the environment the cartridges are stored in. In a vacuum and very clean surfaces (no sweat or moisture from your hands on the copper jacket, it could be a very long time since the dissimilar metal issue is low (brass being an alloy of copper, assuming we're talking about copper jackets in brass cases) as there's a low potential between the two metals. Unless a sealant is used in the neck, air and whatever is in it (like salty air near the ocean or chemicals stored nearby) can seep into the neck area and cause that "cold welding". It could also be any any residual chemical left a cleaning process that cause the copper and brass to, in effect, corrode and meld together. Amount of time can be different just because of the different in the ratios of metal in the alloy. How long any of that takes is a matter of the amount of solution concentration, with heat and changes in ambient temperatures over time. So, the amount of time can be anybody's guess.
When that all said, my own experience for the way I load and store my cartridges, I've noticed a bit of unusual resistance to seating the bullet deeper after sitting around for ~6 months. That's when I taken them to the range and went to adjust the seating depths a little lower, they'd resist more, something with a slight jerky pop, unlike when I'd do it soon after loading the cartridges (.308 cartridges BTW).
PS: as an aircraft mechanic working on airframes, it was not unusual for me to see corrosion between two metals of the same alloy . . . almost always due to the environments. Coatings/sealants, like zinc chromate for aircraft parts, helps a lot with that. .
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Doesnt happen. Its just the brass trying to return to its original shape. My guess.
GOogle- Requires 5000 Psi minimum to cold weld copper to copper. Must be extra clean surfaces.
searcher
Gold $$ Contributor
As said before, depends on length of time and conditions stored in. In most ammo situations with properly stored ammo, one won't see much (if any) difference. That said, I had some factory loaded Winchester .375 H&H ammo that I bought about 25 years ago for the brass. A few years back, I finally needed the brass and pulled the bullets. I'll just say those bullets were a BEAR to get out. They were stored in an insulated workshop relatively near the coast, subjected to relatively low, though somewhat salty humidity - and not sealed in plastic - just the cardboard boxes with the plastic shell holders. I load a lot of varmint ammo, which might not be shot for a while. I put the ammo in plastic jugs and drop in an oxygen absorber before I seal it up. Have never had issues doing that. For my "emergency" home defense and hunting ammo, I vacuum bag it lightly with an oxygen absorber inside the pack. I've pulled enough bullets on older ammo to know it is an issue over time. I'm surprised this is even debated by long-time shooters. I'm guessing they live in very arid areas?
Technically . . . you're right.
That's a small part of it. . . like having to do with "neck tension".
When reloaders mention "cold welding" or "cold melding", the term is used in a very loose sense and referring to when a bullet is sticking to the neck more so over time. It's a misnomer (and why I put it in quotation marks in my response) for what's going on, but it's apparently an easy way to reference the issue. . . especially when one has little or no knowledge in the science of metallurgy.
Maybe it's better to think of it as a galvanic corrosion issue than a cold welding one?
fatelvis
Silver $$ Contributor
Yes, when I originally asked the question, I realize that actual welding does not take place. There is, however, some kind of bonding that takes place over time. I myself have seated bullets deeper after several years and heard and felt a “pop”, and the bullet starts to move, indicating some sort of bond. I just started using Neo lube before seating bullets, because I found that it does bring down the standard deviations, and I hope that it will insulate against this bonding effect.
ELR LVR
Silver $$ Contributor
I have experienced it within a year, noticed some 22 BR were very hard to kinetic pull the bullets compared to freshly loaded
Such as 12 smacks vs only 4
Unless - there is a possibility that brass retracts more in tension over long periods of time
when I inspected, I saw no corrosion of any sort in the cases, the bullets looked clean
I resorted to seating them deeper to break the contact... then pull them
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I am figuring Hbn Coating will also cure this
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I am also thinking this could be a big reason for erratic loads when pulling out some pre loaded ammo that has been sitting
ELR LVR
Silver $$ Contributor
Yes sir,
a Galvanic type of reaction, 2 dissimilar metals have an electrical difference in potential in their valence shell - which starts an ionic transfer on the surface
Same reason Anti-freeze becomes charged over time from the potential difference of ALum and Iron, and begins internal ionic engine corrosion. (bad head gaskets, water pumps etc)
On bullets - it can be worse if the surface has been wet
which can easily happen from just the moisture content of our fingers
which is almost always present
Go touch a mirror even if your hands are thought to be dry, then see if there is moisture on the mirror when you pull your finger away and this will be evident. Or a flat polished piece of steel.
Then there are people who are more prone to have sweaty hands at times - (Salt Content)
Certain times for certain operations, I will thoroughly wash then dry my hands near the fire before conducting an operation to try and dry my hands and fingers as much as possible
---Such as when doing triggers, to prevent sear surface contamination
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