Have you had any experience with "cold welding" of bullets in case necks?

[Forum Boss]

Cold welding is a known phenomenon, but I'm not sure that's the primary cause of the issues being noted here. What I have seen is that necks can stiffen and become less "springy" over time. This results is more force being required to seat (measured with a K&M arbor with force gauge), and/or more force required to re-seat bullet deeper.

In a thread about this sometime ago, a post was made by a Forum member who was a plumber. He said that, in his professional experience, copper tubing definitely changed its flexiness/malleability over time, and this was not simply a function of oxidation of outer layers.

YMMV. I think the most important thing, for accuracy purposes, is to seat all bullets for a match within a reasonably short period of time, or at least keep your "aged brass" ammo separate from very recently sized and loaded brass.

It would also be interesting to see how annealing before loading might affect all of this.

PM

 

[BoydAllen]

Forum Boss,
What I am inquiring about, and what several of us have recounted, in our posts, is not the effect that you described. It is not the stiffening of necks that have previously been sized so that seating bullets requires more force than it would have if they were seated immediately after sizing. I have experienced what you described and this is not the point under discussion. The reason that some may not "get" this is simple. They have not experienced it. It sounds like you belong to that fortunate group ;D When bullets bond in necks the amount of force needed to break them loose increases by (just guessing) perhaps a factor of ten or more. Once they have been broken free, they may be pulled or seated deeper with no difficulty. The pop that is heard when they break loose is loud and unmistakable. If I wanted to make this happen for purposes of demonstration, I would use a drill to spin a bronze brush inside of a case neck that had been sized to produce a fairly high neck tension until fouling or corrosion was visible, degrease the neck interior and bullet with acetone, while wearing rubber gloves, so as not to "contaminate" the bullet with skin oil, and seat the bullet. Under these conditions, I feel confident that within a couple of months, perhaps much sooner, an attempt to seat the bullet deeper would cause the great increase in seating pressure and the popping sound that has been described. I realize that we do not load this way, but this is my idea for taking the conditions that produce the effect to the extreme.

 

[jlow]

Cold fusion set aside for a second, my question is what is the effect of the neck of the brass becoming less “springy” over time (as per Forum Boss’s comments) assuming that the bullet has already been seated i.e. we are now no longer looking at seating pressure but possible effect on extraction pressure?

 

[in2deep]

This welding is especially pronounced when you over-clean inside the necks and I noticed it after going to the stainless media which gets everything out of the neck and I believe that the brass and copper jackets do somehow form a bond over time so I don't load more than a week or so before firing when possible.
It was discovered when using a hand die and arbor press while re-seating some bullets deeper for a ladder test after they sat around for 6 weeks and the seating force was noticeably much harder and took considerable effort to get the bullet moving.
It was so bad that I pulled a bullet thinking I overcharged the cases and was compressing the powder but it was not.

BUT....I have shot rounds that were stored and "welded" and honestly they shot just as good as the freshly loaded rounds and possible inducing 50 gamillion psi behind those little buggers is a great equalizer.

 

[300 RUM]

Anyone interested in an experiment?
To anyone who has this POPING take place, if you would send me your loaded round or pulled bullet and case I can examine these rounds in my lab and check to see what is actually going on. If interested contact me off line.

 

[jlmurphy]

I think that seating hard into the rifling might minimize the possible change in neck tension from long term stored ammo.

 

[johara1]

I pulled thousands 173 bullets from lake city 308's and never once had any of what you call cold welding happen. Does it take more force to pull them than it did to seat them? it should. If you torque a barrel to 50 ft.lb and go to remove it you have to over come the 50 with more. Same with a seated bullet I don't buy this cold welding unless you and a third factor, they are not dissimilar metals. You as the loader would have to add something to cause this....jim

 

[bozo699]

I pulled thousands 173 bullets from lake city 308's and never once had any of what you call cold welding happen. Does it take more force to pull them than it did to seat them? it should. If you torque a barrel to 50 ft.lb and go to remove it you have to over come the 50 with more. Same with a seated bullet I don't buy this cold welding unless you and a third factor, they are not dissimilar metals. You as the loader would have to add something to cause this....jim

Jim,
I don't know the correct term,..cold welding,...stuck bullet,...or whatever but I have had this happen more then once and not months or years after the rounds were loaded but just a few days, three days I think it was the last time it happened to me. I used a K&M arbor press with force seat measurement, and when I seated the bullets into the case with .001 neck tension it took .015-.020 to seat the bullets three or four days later it took .200 plus to break them free, I thought I was going to break the handle off the arbor press,...I am not kidding and I am not a liar,...it happened!! I later found that by brushing the necks real good with a nylon brush this didn't seem to happen, I had been cleaning the necks squeaky clean, I now just brush them, I don't have the answers I just know it has happened to me on occasions, I pulled some 25-06 cases I loaded 15 or 20 years ago that I literally pulled the jackets off the bullet trying to pull them with a rcbs collet puller, I found by clamping the collet to the bullet and seating it in a few thousands I could then pull the bullet but even then I deformed it. Like I said I don't know the correct term nor have the answers but I know there is something to it.
Wayne.

 

[Tozguy]

This 'cold welding' reminds me of what we called 'stiction' in motorcycle suspensions. It referred to static friction which was always higher than dynamic friction of the oil seals and wipers in the front forks. The larger the diameter of the fork tubes the more it was obvious everything else being equal. New low friction fork seal materials have largely reduced stiction in modern larger diameter fork tubes to barely noticeable levels.
The 'pop' that Boyd is referring to as I understand it is along the same lines ie. caused by static friction rather than corrosion or bonding. Obviously some friction is necessary to hold the bullet. There are probably a number of factors that determine how much 'pop' you feel when reseating a bullet but there is no doubt in my mind that 'stiction' exists at some level in all our ammo.

 

[bozo699]

This 'cold welding' reminds me of what we called 'stiction' in motorcycle suspensions. It referred to static friction which was always higher than dynamic friction of the oil seals and wipers in the front forks. The larger the diameter of the fork tubes the more it was obvious everything else being equal. New low friction fork seal materials have largely reduced stiction in modern larger diameter fork tubes to barely noticeable levels.
The 'pop' that Boyd is referring to as I understand it is along the same lines ie. caused by static friction rather than corrosion or bonding. Obviously some friction is necessary to hold the bullet. There are probably a number of factors that determine how much 'pop' you feel when reseating a bullet but there is no doubt in my mind that 'stiction' exists at some level in all our ammo.

New word of the day,.....'stiction' I like it
Wayne.

 

[BoydAllen]

It has been a long time since I pulled apart any military ammo, but on some of the old stuff that I looked at, the inside of the case necks were coated with an asphaltic material, which should make cold welding impossible. Give this thread a read.
http://450bushmaster.net/viewtopic.php?f=5&t=1084


Again, the pop is a loud SOUND, and the force it takes to break a cold welded bullet free is perhaps ten times the force it takes to move it after breaking it free. If you have not HEARD the pop, you are among those who have not experienced this phenomenon.

 

[Heavies]

My theory on this...

As the forum boss had mentioned the brass spring back can continue after the neck has been sized. The older threads mention that brass sized with a bushing type die, with no expander, seems to keep 'getting tighter' as time progresses. I believe the brass is continuing to 'flow' in the direction of the sizing operation. That, in my view, is what causes the bullets to seat with more force if the case is not loaded shortly after the sizing operation. This flow will stop at some point, where I do not know.

The reason I have come to this conclusion is that when I size with a neck die such as the Lee Neck sizer, which the neck is pressed onto a center mandrel, and left to sit a few days, the seating force seems to get easier, as the brass has been effectually sized from the inside out.
If bullets are seated right after sizing, the force required is noticeably more than if the case has been left to sit for a few days.

Now, if the sizing operation (bushing type) has been done, and the bullets are seated in a timely fashion, I do not believe the 'flow' has been halted. Even thought the seating force seemed small, as time progresses, the neck is actually getting a tighter grip around the bullet.

This I believe is the pop that is occurring on these rounds.

This would be on rounds that are sitting short term. Older MILSUP rounds, I believe, may be suffering from this, as well as, the galvanic type corrosion, sticking the neck to the bullet.

This is just my theory, and I have no way of proving any of this, but this is what I have observed.

 

[bozo699]

My theory on this...

As the forum boss had mentioned the brass spring back can continue after the neck has been sized. The older threads mention that brass sized with a bushing type die, with no expander, seems to keep 'getting tighter' as time progresses. I believe the brass is continuing to 'flow' in the direction of the sizing operation. That, in my view, is what causes the bullets to seat with more force if the case is not loaded shortly after the sizing operation. This flow will stop at some point, where I do not know.

The reason I have come to this conclusion is that when I size with a neck die such as the Lee Neck sizer, which the neck is pressed onto a center mandrel, and left to sit a few days, the seating force seems to get easier, as the brass has been effectually sized from the inside out.
If bullets are seated right after sizing, the force required is noticeably more than if the case has been left to sit for a few days.

Now, if the sizing operation (bushing type) has been done, and the bullets are seated in a timely fashion, I do not believe the 'flow' has been halted. Even thought the seating force seemed small, as time progresses, the neck is actually getting a tighter grip around the bullet.

This I believe is the pop that is occurring on these rounds.

This would be on rounds that are sitting short term. Older MILSUP rounds, I believe, may be suffering from this, as well as, the galvanic type corrosion, sticking the neck to the bullet.

This is just my theory, and I have no way of proving any of this, but this is what I have observed.

Heavies,
I don't use a Collet die much, I do use just not much so I can't comment there but I have noticed the opposite with other dies, opposite by meaning the longer they sit sized the harder they seat, that has just been my observation anyway. As far as galvanic corrosion according to the anodic index copper is .035V and brass is .040V which is a .005V difference, typically you need around .015V difference to have this galvanic corrosion to take place in extreme environment conditions and .050V in controlled environment conditions so I don't think galvanic corrosion or cold welding exists in this case but something is going on for sure!
Wayne.

 

[Heavies]

My theory on this...

As the forum boss had mentioned the brass spring back can continue after the neck has been sized. The older threads mention that brass sized with a bushing type die, with no expander, seems to keep 'getting tighter' as time progresses. I believe the brass is continuing to 'flow' in the direction of the sizing operation. That, in my view, is what causes the bullets to seat with more force if the case is not loaded shortly after the sizing operation. This flow will stop at some point, where I do not know.

The reason I have come to this conclusion is that when I size with a neck die such as the Lee Neck sizer, which the neck is pressed onto a center mandrel, and left to sit a few days, the seating force seems to get easier, as the brass has been effectually sized from the inside out.
If bullets are seated right after sizing, the force required is noticeably more than if the case has been left to sit for a few days.

Now, if the sizing operation (bushing type) has been done, and the bullets are seated in a timely fashion, I do not believe the 'flow' has been halted. Even thought the seating force seemed small, as time progresses, the neck is actually getting a tighter grip around the bullet.

This I believe is the pop that is occurring on these rounds.

This would be on rounds that are sitting short term. Older MILSUP rounds, I believe, may be suffering from this, as well as, the galvanic type corrosion, sticking the neck to the bullet.

This is just my theory, and I have no way of proving any of this, but this is what I have observed.

Heavies,
I don't use a Collet die much, I do use just not much so I can't comment there but I have noticed the opposite with other dies, opposite by meaning the longer they sit sized the harder they seat, that has just been my observation anyway. As far as galvanic corrosion according to the anodic index copper is .035V and brass is .040V which is a .005V difference, typically you need around .015V difference to have this galvanic corrosion to take place in extreme environment conditions and .050V in controlled environment conditions so I don't think galvanic corrosion or cold welding exists in this case but something is going on for sure!
Wayne.

I see. Thank you. I never knew that about galvanic action. I always thought that any type of dissimilar metals would be susceptible to this type of action.

For the record, I too find that seating long, then re-seating to the correct length right before a match helps out with consistency. That is when I don't procrastinate and load the night before anyway. haha ;D

 

[johara1]

Boyd, If you ever shot lake city you would know it didn't have the sealer like ball ammo. So why didn't happen there? all we did was replace the 173 with 168's. That brass was so good you could neck it down to 243 and back to 308 and then to 358 and it never cracked. maybe the brass it happens with is lower quality? loader induced?.....jim

 

[BoydAllen]

Since I have no experience with the ammunition that you referred to, it would be impossible for me to know why it has not had the problem, but a friend has told me that a light waxing of the bullets prevents the problem. Perhaps there were some residual forming lube, that would not interfere with putting powder in cases that is responsible for your experience. It would seem to be a good idea to use a case drawing lube that was wax based, but my go to answer in these cases, the most honest is... I DON'T KNOW ;D The experience mentioned in other posts is that clean dry components tend to have the problem. Since new components do not have any firing residue at their interface, perhaps there is something there that is not easily seen, but which prevents the problem. Maybe I need to ask a couple of ammo manufacturers what they know about this issue. I am sure that I would learn a lot.

On the quality of Lake City 5.56 brass: A while back, a friend was given a good quantity of fired brass, all from the same lot. Before doing anything with it, he asked me what I knew about the quality. I told him that what I had worked with was excellent, better than a lot of commercial brass that I had tried. Despite that he seemed to be of the mind that it was probably true that brass made for the military might not be made to as high of a standard. This went back and forth a few times, during the conversation. Some time later, after he had run quite a bit of it over a gauge that he made that allows him to look at body thickness runout, he told me that the brass was indeed very good. In fact, I believe that since the batch was large enough to cover his need for any given varminting excursion, he retired most of his other brass in favor of the Lake City. I understand that there are lot to lot variations in any brass, but my impression of Lake City is that it is well above average.

 

[TC260]

Now, if the sizing operation (bushing type) has been done, and the bullets are seated in a timely fashion, I do not believe the 'flow' has been halted. Even thought the seating force seemed small, as time progresses, the neck is actually getting a tighter grip around the bullet.

Interesting discussion guys. I've also experienced the stuck bullet phenomenon although not with my reloads (I don't store loaded ammo for any real length of time. Few months during deer season is about max).

I'm not sure I'd go along with the "grip" of the neck getting tighter (as in more neck tension). If it were, I'd think when we reseated the bullet the amount of friction wouldn't immediately decrease after "the pop". It would continue to be difficult to move the bullet regardless.

However, it makes sense to me that the brass still has the ability to "flow" after sizing as you mentioned. At least on a molecular level it makes sense. After the bullet is seated, maybe the brass continues to "flow" over time to fill the microscopic (think molecular level) voids between the bullet and case that's leading to cold welding. Or maybe there is no "cold welding" (molecular bonding) but the friction is increased because of the two materials physically "molding" together on a microscopic level. It's easy to forget but even what looks like very smooth surfaces to us are very "rough" on a microscopic level.

If the peaks and valleys of two materials can flow together, that greatly increases the amount of surface area contact between the two. Once the bullet is moved, either the cold welded bonds or the molded surfaces are broken (whichever phenomenon is actually at work) and the bullet moves freely again.

 

[johara1]

Do you think that maybe it would have something to do with the neck expander? I have never used one and never saw this problem and i don't use any lube other than imperial wax nothing inside the neck. I only use light neck tension also. I use a q tip to clean any wax that may have gotten in the neck. I can only guess because i don't have the problem.......jim

 

[bozo699]

Do you think that maybe it would have something to do with the neck expander? I have never used one and never saw this problem and i don't use any lube other than imperial wax nothing inside the neck. I only use light neck tension also. I use a q tip to clean any wax that may have gotten in the neck. I can only guess because i don't have the problem.......jim

Jim,
I know you haven't had the problem and I know I have,...it's funny though because we prep the same, I keep a couple bags of commercial q-tips on hand at all times for little things just like that

My theory on this...

As the forum boss had mentioned the brass spring back can continue after the neck has been sized. The older threads mention that brass sized with a bushing type die, with no expander, seems to keep 'getting tighter' as time progresses. I believe the brass is continuing to 'flow' in the direction of the sizing operation. That, in my view, is what causes the bullets to seat with more force if the case is not loaded shortly after the sizing operation. This flow will stop at some point, where I do not know.

The reason I have come to this conclusion is that when I size with a neck die such as the Lee Neck sizer, which the neck is pressed onto a center mandrel, and left to sit a few days, the seating force seems to get easier, as the brass has been effectually sized from the inside out.
If bullets are seated right after sizing, the force required is noticeably more than if the case has been left to sit for a few days.

Now, if the sizing operation (bushing type) has been done, and the bullets are seated in a timely fashion, I do not believe the 'flow' has been halted. Even thought the seating force seemed small, as time progresses, the neck is actually getting a tighter grip around the bullet.

This I believe is the pop that is occurring on these rounds.

This would be on rounds that are sitting short term. Older MILSUP rounds, I believe, may be suffering from this, as well as, the galvanic type corrosion, sticking the neck to the bullet.

This is just my theory, and I have no way of proving any of this, but this is what I have observed.

Heavies,
I don't use a Collet die much, I do use just not much so I can't comment there but I have noticed the opposite with other dies, opposite by meaning the longer they sit sized the harder they seat, that has just been my observation anyway. As far as galvanic corrosion according to the anodic index copper is .035V and brass is .040V which is a .005V difference, typically you need around .015V difference to have this galvanic corrosion to take place in extreme environment conditions and .050V in controlled environment conditions so I don't think galvanic corrosion or cold welding exists in this case but something is going on for sure!
Wayne.

I see. Thank you. I never knew that about galvanic action. I always thought that any type of dissimilar metals would be susceptible to this type of action.

For the record, I too find that seating long, then re-seating to the correct length right before a match helps out with consistency. That is when I don't procrastinate and load the night before anyway. haha ;D

Heavies,
I have to confess,..I never did either, I looked it up during this conversation ;D

http://www.engineersedge.com/galvanic_capatability.htm

There were several other articles I read as well, Jim stated they are not dissimilar metals, I thought maybe he was wrong, they are but not enough to cause the "cold welding process"
This is a very interesting thread Boyd started for sure.
Wayne.

 

[jo191145]

Now, if the sizing operation (bushing type) has been done, and the bullets are seated in a timely fashion, I do not believe the 'flow' has been halted. Even thought the seating force seemed small, as time progresses, the neck is actually getting a tighter grip around the bullet.

Interesting discussion guys. I've also experienced the stuck bullet phenomenon although not with my reloads (I don't store loaded ammo for any real length of time. Few months during deer season is about max).

I'm not sure I'd go along with the "grip" of the neck getting tighter (as in more neck tension). If it were, I'd think when we reseated the bullet the amount of friction wouldn't immediately decrease after "the pop". It would continue to be difficult to move the bullet regardless.

However, it makes sense to me that the brass still has the ability to "flow" after sizing as you mentioned. At least on a molecular level it makes sense. After the bullet is seated, maybe the brass continues to "flow" over time to fill the microscopic (think molecular level) voids between the bullet and case that's leading to cold welding. Or maybe there is no "cold welding" (molecular bonding) but the friction is increased because of the two materials physically "molding" together on a microscopic level. It's easy to forget but even what looks like very smooth surfaces to us are very "rough" on a microscopic level.

If the peaks and valleys of two materials can flow together, that greatly increases the amount of surface area contact between the two. Once the bullet is moved, either the cold welded bonds or the molded surfaces are broken (whichever phenomenon is actually at work) and the bullet moves freely again.

Impressive first post 8) You may be on to something there. As good a theory as any.

On the subject of disimiliar metals. Is it possible to gall a SS barrel while screwing it dry into a SS action?