Dry graphite before seating bullet

I have heard about bullet weld after sitting. If you were to load and shoot within a few weeks, is there a functional difference in accuracy? I generally notice about 10 fps more without and a bit higher sd but not sure how much it actually matters on target.
Not only does it matter on target, it can also cause pressure issues. I had a rifle I experienced weld in and my load went from perfectly fine to bolt lift with swipe and a high miss at distance. Did some research and narrowed it down to being bullet weld, bumped the loaded ammo with a seating die and you can hear an audible crack of the bond breaking. Have used graphite and not had an issue since.
 
This whole conversation, here and elsewhere, is making me wonder a couple of things:

1) How much of this is just from necks snapping back into place more tightly over time, after sizing? I've seen this happen after waiting a few weeks between sizing and loading.

2) If cold-welding is actually a thing, and you want to load up a few hundred rounds for a gun you don't shoot often, and they might last a few years - how long would you need to wait after the initial load to get an accurate representation of how accurate it will be after sitting for months or years? It sounds ridiculous, but if cold-welding is a thing, then should we all be doing our load development with sets of loads "seasoning" for a few months before actually running groups with them, or something?

I keep reading about this cold-welding thing in obscure corners of the reloading world, but something still doesn't seem right about the explanations. I suppose using hex-boron or moly in the necks might help or prevent it from happening, but something still seems off about what's really going on, why, and how to deal with it.
 
This whole conversation, here and elsewhere, is making me wonder a couple of things:

1) How much of this is just from necks snapping back into place more tightly over time, after sizing? I've seen this happen after waiting a few weeks between sizing and loading.
Any evidence? The way I understand it the brass doesn't shrink, once a mandrel or ball is ran through it the springback occurs immediately after it leaves, and the inner diameter is set.

2) If cold-welding is actually a thing, and you want to load up a few hundred rounds for a gun you don't shoot often, and they might last a few years - how long would you need to wait after the initial load to get an accurate representation of how accurate it will be after sitting for months or years? It sounds ridiculous, but if cold-welding is a thing, then should we all be doing our load development with sets of loads "seasoning" for a few months before actually running groups with them, or something?
Or you could just use lube and it's consistent.

I keep reading about this cold-welding thing in obscure corners of the reloading world, but something still doesn't seem right about the explanations. I suppose using hex-boron or moly in the necks might help or prevent it from happening, but something still seems off about what's really going on, why, and how to deal with it.
In my case it occurred in fired brass that I ran a nylon brush through the neck, and loaded 100 rounds for the season. 6-8 months or so later I went to the range to do some shooting and noticed the issues. After some research I physically experienced it by feeling and hearing the bond break from bumping bullets in the seating die. I bought Redding graphite lube and now dust necks before seating, and haven't had an issue since. So the interference of brass, carbon, and copper can cause a bond, graphite will prevent it. If you search on the interwebs enough you'll find quite a few accounts where handloaders that pay close attention have experienced it as well.
 
I have always wondered how factory ammo gets around bullet welding. Factory ammo is almost always heavily crimped, perhaps the extra pressure to release the crimp helps expand the neck slightly and break any welding before the bullet starts moving? Is there a lubricating step on automated lines that we don’t see and if so what kind of lube? I can’t ever remember reading an article that mentioned it.
 
I have always wondered how factory ammo gets around bullet welding. Factory ammo is almost always heavily crimped, perhaps the extra pressure to release the crimp helps expand the neck slightly and break any welding before the bullet starts moving? Is there a lubricating step on automated lines that we don’t see and if so what kind of lube? I can’t ever remember reading an article that mentioned it.
My guess is no carbon.
 
My guess is no carbon.
I understood that cold welding occurs when there are no other chemicals/elements between the copper bullet and the copper-alloy case.

Graphite is carbon, so when you use graphite lube, you are adding carbon to the neck. I have also seen ELR/accuracy pros recommend dry media tumbling before annealing specifically so that annealing with the media dust in the neck will leave a light coating of carbon to prevent cold welding.
 
There should be a separate thread on cold welding for everyone to provide their experiences, what's worked and what hasn't, and maybe get a discussion going for figuring out a definitive method to prevent it.

I've used imperial dry graphite on my case necks a ton, but still get cold weld.

My process is:
- anneal every few firings
- brush inside neck with nylon brush
- lube case, dip neck in graphite, size, wipe off lube
- prime
- powder, seat bullet

This process has given me cold weld, even after the cases have many reloads on them and there's a significant carbon layer on inside of the neck.

It's possible that:
- annealing burns the carbon off enough it exposes some bare brass
- using graphite only before sizing doesn't leave enough graphite for bullet seating
- expanding mandrel/button scrapes some carbon off exposing brass
- not wearing gloves while handling and seating bullets gets some salt/oils from my skin on the bullet and promotes welding

This year at some point, I'm going to test 5 rounds each of those potential sources I've thought of. I want to be able to load hundreds of rounds at once and have them perform the same way months later without having to break the bond.

Back to the use of graphite.... I've found that it makes bullet seating smoother but have not seen any benefit in the context of accuracy or velocity spreads. So, I want to cut it out of my process if possible.
 
There should be a separate thread on cold welding for everyone to provide their experiences, what's worked and what hasn't, and maybe get a discussion going for figuring out a definitive method to prevent it.

I've used imperial dry graphite on my case necks a ton, but still get cold weld.

My process is:
- anneal every few firings
- brush inside neck with nylon brush
- lube case, dip neck in graphite, size, wipe off lube
- prime
- powder, seat bullet

This process has given me cold weld, even after the cases have many reloads on them and there's a significant carbon layer on inside of the neck.

It's possible that:
- annealing burns the carbon off enough it exposes some bare brass
- using graphite only before sizing doesn't leave enough graphite for bullet seating
- expanding mandrel/button scrapes some carbon off exposing brass
- not wearing gloves while handling and seating bullets gets some salt/oils from my skin on the bullet and promotes welding

This year at some point, I'm going to test 5 rounds each of those potential sources I've thought of. I want to be able to load hundreds of rounds at once and have them perform the same way months later without having to break the bond.

Back to the use of graphite.... I've found that it makes bullet seating smoother but have not seen any benefit in the context of accuracy or velocity spreads. So, I want to cut it out of my process if possible.


Another, independent thread on cold welding would be a great idea.

Also, this is definitely one of those gun areas where people will tend to respond with "Well, I've been using it ___ years, and I've never had a problem with it", but graphite can actually enhance galvanic corrosion.

Between copper and brass, graphite can increase the rate of the corrosion of the zinc in the brass, in the presence of some moisture. I don't know how much of any of that it takes, but moly and hex boron do not cause those issues as dry, powdered lubes.
 
...

Between copper and brass, graphite can increase the rate of the corrosion of the zinc in the brass, in the presence of some moisture. I don't know how much of any of that it takes, but moly and hex boron do not cause those issues as dry, powdered lubes.

Interesting! I have not messed with dry neck much at all that is food for thought before adding a step to the process.
 
There should be a separate thread on cold welding for everyone to provide their experiences, what's worked and what hasn't, and maybe get a discussion going for figuring out a definitive method to prevent it.
Another, independent thread on cold welding would be a great idea.
Started a new thread in the reloading forum.
 
Electron migration is very real and water based case lube would be an excellent conductor, but it will happen even without it.
Physical separation is one way to mitigate this, ie a heavy carbon buildup from dirty brass, but with clean brass and bullets a dip in graphite won’t do very much because the layer, if it is present will be so thin.

The above is all theoretical but based on proven scientific information
 
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