Bullet weld and pressure relationship

[chop house]

Curious if you would be able to take a snapshot of the inside of that case neck?

great idea... yet another use for a teslong...

 

[6Creed73]

The mysterious cold weld problem that doesn't happen with factory ammo.

Maybe it's just your fingerprints on the bullets causing corrosion. Some people have very acidic fingerprints... Do you load with bare hands?

I wear nitrile gloves while reloading, always have. Curiously, I've never seen this "cold welding" phenomenon.

Some even brag about using a paper towel etc to wipe off sizing lube. How sure are those folks, that they aren't contaminating cases and bullets with lube/finger-sweat that could do weird stuff with time?

I'm not willing to declare that it doesn't happen with factory ammo. I think it's more likely that it's just not noticed and it's probably less likely that people are breaking down factory ammo.

My guess is an explosion happening in a millisecond is much more effective at breaking the weld than some guy pulling on a lever with a press. Other than accuracy suffering, the shooter may not even realize anything is amiss

 

[asquared19]

So what could we consider as the failsafe option for reloaded? I am preparing to do some loading in the near future. Some I intend to shoot within 12 months, some will just be stored, potentially for a few years. Aside from keeping them In a climate controlled space, inside a good storage box (ie ammo can) with desiccant packs, what can we do to be ensure safety? Both with pistol and rifle rounds.

 

[46and2]

I believe that it is caused by electrolysis between the two dissimilar metals. Even though brass and copper are kind of similar. (my theory and I'm sticking to it)

I do know that is a a real thing. I also never thought much about it until a while back I shot some 270 shells I loaded prolly 20 years ago. They shot horrible (about 3 MOA) and I decided to break them down and try some different things. A few shells in I was pretty amazed at the bond between bullet and neck. I had to bust them loose with my seater die, then pull. jd

Yes, Galvanic Corrosion

 

[6Creed73]

"So what could we consider as the failsafe option for reloaded?"

Using graphite powder or Neo lube #2 inside the case neck should mitigate it. I've been doing that anyway the past couple of years because it gives me more consistent bullet seating.

 

[jds holler]

I bought a 30-06 Mauser Sporter back in the seventies. The army surplus store in our town had surplus ammo for me dated from Korean War vintage - 1950 sump thin. As I recall, both bullets and primers were cemented. Ammo was black tipped bullets. It shot very well in my new rifle.

Cemented bullets would create their own version of "bullet weld" but probably not as serious as galvanic weld. And the cement would actually prevent the metal to metal contact that facilitates that weld. jd

 

[ballisticdaddy]

Curious how every firearm that has ever fired surplus ammunition has survived and not blown up due to the overpressure from galvanic corrosion? Why doesn't all factory ammunition have an expiration date? Why has my hand loaded 6BR ammo that has sat inside my safe in the non temperature controlled garage still able to shoot clean targets at 600 yards after sitting for over a year?

 

[searcher]

I was wondering about this myself. Up until I struggled breaking these down today, I never gave cold welding a second thought. But it's now obvious to me that it can and does happen. What I'm still unsure about is if I decided to shoot these instead of breaking them down, would I even have noticed an issue.

But given how much force it took to pull the bullets, I can't believe there isn't some kind of pressure spike, even if it's a somewhat small spike.

I barely remember reading something about the Army testing the cold welding phenomenon and confirmed it does happen but determined that it caused no negative affects. This was years ago that I read it and unfortunately I can't find it, nor can I remember where I read it.

Every year, millions of government ammunition rounds are taken apart under government contract. The powder is checked and sold as pulldown powder. I do not know for fact why they do this - but I'm guessing they sample batches that are checked to ensure the ammo still meets certain criteria as to condition, pressure, accuracy, etc. We know bullets can last decades when stored properly from the elements. Same with powder and primers. Cold welding comes to mind as the primary logical reason for the need to pull that ammo apart in most cases. I've bought pulldown bullets before and one can tell by looking at the bullets, there was tremendous friction when the bullets were pulled, occasionally ruining the bullet to get it out of the case. I have never had a problem pulling a bullet that was recently seated, no matter how much neck tension or crimp. But - I've pulled a lot of bullets from ammo which were 5 to 10+ years old and that is a whole different story. They are ALWAYS harder to get out, with exception to bullets I moly coated. And that WILL result in increased and/or erratic pressure.

 

[SeabeeKen]

During my military career (76-98), I pulled down 5.56 ammo and found they all had an asphaltic sealer in the necks to make them waterproof. All pulled fine and I suspect the asphalt acts as a lubricant/anti-sieze.
Back in the 90's I had rounds that cold welded and I had to seat them deeper to break the bond and they had a noticeable pop when they broke free and in a few cases the seating stem left indentations in the bullet jacket. Ever since then I use a neck lube. Started with graphite and then went to Lee case lube and I have been using it ever since and never another issue.

 

[searcher]

Curious how every firearm that has ever fired surplus ammunition has survived and not blown up due to the overpressure from galvanic corrosion? Why doesn't all factory ammunition have an expiration date? Why has my hand loaded 6BR ammo that has sat inside my safe in the non temperature controlled garage still able to shoot clean targets at 600 yards after sitting for over a year?

MANY surplus firearms HAVE blown up using surplus ammo. I've personally witnessed a few at the range myself. While many think the gun was "old and at fault", the likely reason was that ammo. But there is the distinction of most surplus ammo being in good shape - and some not so. Those using prudence wouldn't try to fire the really ratty stuff - but someone always does.

I've had .45 ACP old military ball ammo that I wouldn't shoot without the gun being in a ransom rest and I being 20 feet away with a string..... You could see the electrolysis forming a white powdery ring, bonding the bullet to the case. I tried pulling some bullets and it tore the rims off the brass in the shell holder before the bullet let loose.

Regarding your 6BR ammo, while you still shoot clean targets, I doubt your ES's are as good as when you worked up that load or last tested it on a chrono. But that doesn't necessarily mean it has degraded to the point you can't shoot well with it. A year of storage is not going to cause the type of welding that could be encountered with some lots of military surplus. It also depends on how cases are cleaned prior to loading. If one cleans the cases to bare, shiny brass, he is going to have more cold welding issues than someone who just runs a brush through the neck a time or two. If bullets are moly coated, cold welding is usually undetectable.

I think putting expiration dates on ammo would be pretty dubious. Well-kept ammo could last for decades. Poorly stored ammo in high humidity might be toast in several years or less. I can already see a lawsuit because some joker blew his gun up with poorly stored ammo - while citing the "expiration date" was not yet reached. They chose to say "Store in a cool, dry location". EDIT: Somone wanted to know how old those .45 ACP rounds were. I'm guessing Vietnam War Era or older......

 

[K22]

I have never paid attention to this issue but then again, I have never had reloads sit around for more that 18 months. I often load in the winter months for upcoming varmint season in the spring and summer. I could never detect any changes in performance but then again, I really never conducted a structured comparison test.

In response to a previous thread on this issue regarding accuracy, I have set out to conduct an experiment consisting of loading 10 rounds with the established base to ogive length, and 10 seated 0.050", to be reseated after 12 months or so and see if there is a discernable difference in accuracy between the two test samples.

However, this thread gotten my attention because of the safety aspect some of the posters have posted.

 

[Straightshooter1]

I've had some .308 cartridges that I've loaded sit for about months that had a little this welding issue. I had loaded them long as I planned to seat them to my desired depth at the range just before using. When I did so, I noticed a initial and distinct abrupt like pop as the bullet was seated down. Later I took some back to my work bench to test to test and get some idea what that was all about. I seated a couple, like before, then pulled them with my collet puller and they came out easy as expected and with no apparent scaring on the bullet's surface. I pulled a couple of the others that had not been touched for 6 months and they were defiantly a little harder to pull, but still no apparent scaring on the bullets. As far as what happened on the range, found nothing unusual about what I got on target nor for the velocities. Whatever welding there was, it had no noticeable effect. BTW: it's very unusual that I'd have cartridges that I've loaded sitting around that long.

 

[46and2]

I've had some .308 cartridges that I've loaded sit for about months that had a little this welding issue. I had loaded them long as I planned to seat them to my desired depth at the range just before using. When I did so, I noticed a initial and distinct abrupt like pop as the bullet was seated down. Later I took some back to my work bench to test to test and get some idea what that was all about. I seated a couple, like before, then pulled them with my collet puller and they came out easy as expected and with no apparent scaring on the bullet's surface. I pulled a couple of the others that had not been touched for 6 months and they were defiantly a little harder to pull, but still no apparent scaring on the bullets. As far as what happened on the range, found nothing unusual about what I got on target nor for the velocities. Whatever welding there was, it had no noticeable effect. BTW: it's very unusual that I'd have cartridges that I've loaded sitting around that long.

Do you sonic clean or SS pin tumble your brass? Or were these virgin cases?

 

[Straightshooter1]

Do you sonic clean or SS pin tumble your brass? Or were these virgin cases?

As I can best recall (it's been a few years since), they were previously fired brass and actually wet tumbled without any SS pins (no media at all), so necks still had some carbon residue in them. And because the wet tumbling does cause some case mouth peening, the case mouths were trimmed and chamfered afterwards as the final process. No lube was ever applied for seating purposes.

 

[Walt Schmidlin]

I bought a 30-06 Mauser Sporter back in the seventies. The army surplus store in our town had surplus ammo for me dated from Korean War vintage - 1950 sump thin. As I recall, both bullets and primers were cemented. Ammo was black tipped bullets. It shot very well in my new rifle.

Cemented bullets would create their own version of "bullet weld" but probably not as serious as galvanic weld. And the cement would actually prevent the metal to metal contact that facilitates that weld. jd

Black tipped 30-06 are/were armor piercing !

 

[Downhill]

From what I remember from a metallurgy class, this is probably ionic bonding. Dissimilar metal can bond together over time( something to do with atom structure- got to look it up now). Most common in the heavier and softer metals- gold to lead for example.
But, I am still shooting some Lake City 69 M2 Ball that I got in the early 90's. When we use to make Mexican match, it took a bit of effort to remove the original bullet.

 

[searcher]

During my military career (76-98), I pulled down 5.56 ammo and found they all had an asphaltic sealer in the necks to make them waterproof. All pulled fine and I suspect the asphalt acts as a lubricant/anti-sieze.
Back in the 90's I had rounds that cold welded and I had to seat them deeper to break the bond and they had a noticeable pop when they broke free and in a few cases the seating stem left indentations in the bullet jacket. Ever since then I use a neck lube. Started with graphite and then went to Lee case lube and I have been using it ever since and never another issue.

I've pulled down a fair amount of foreign ammo (like Wolff) just to get the brass back in times of shortages. They also use that black, rubbery sealer. I have wondered if, aside from sealing the case, whether it served as a method to hold the bullet in place without having to crimp, as there was no cannelure on the bullets.

 

[deadidarren]

I've read some stuff in the past about bullets cold welding to the case, I've also seen it called cold soldering. But I've never experienced it until today. I came across an old box of ammo that I loaded about 3 years ago and was pretty stoked because it's Peterson brass. So I decided to break them down to use the brass for some new loads.

I use a collet puller die and these things were an absolute bear to get apart, twice the bullet slipped out of the collet. I tightened the collet down like crazy and then thought I was going to rip my press off the bench or pull the case out of the shell holder before finally breaking it free. The amount of force it took to pull apart is nuts. You can see in the photo that the bullet has some kind of black corrosion or something. And it's important to note that these were found in a box from when I moved a few years ago and the box has been stored in a spare bedroom in the house which is climate controlled.

Anyway, this got me wondering about the pressure spike associated with shooting something like this, especially if the load is already on the high end of max. I was wondering if anyone has seen any studies or write ups about this, I looked but couldn't find anything. I imagine shooting a round like these would have to affect pressure in some way. At the very least, accuracy will be all over the place.

About two years ago I started putting neo lube #2 inside the necks prior to seating...not because I was worried about cold welding, but for more consistent seating. If I had the patience, I'd seat some dummies with neo lube and let them sit for an extended period and see if the bullets pull easily, I'm guessing they would.

View attachment 1499763

I discovered this phenomena around 20 years ago and If you seat the bullet 10 or 15 thou deeper into the case, you will hear it crack and then it is easy to pull-down the ammunition. I know this doesn't help with the question about pressure. Just letting you know there's an easy way of pulling the ammo down .
Hope this helps cheers .

 

[justinp61]

The mysterious cold weld problem that doesn't happen with factory ammo.

Maybe it's just your fingerprints on the bullets causing corrosion. Some people have very acidic fingerprints... Do you load with bare hands?

This is my thoughts too, the natural acids cause the reaction or accelerates it. I'm guessing most factory rounds are loaded on machines and the bullets aren't touched except to dump them in a hopper of some sort.

 

[divingin]

The Army wouldn't be concerned unless the rounds, didn't fire or damaged the firearm. Battle fired brass is not collected. And I doubt even 1 projectile in a 10000 actually hits enemy combatant.

I seem to recall that someone calculated rounds/kill in Vietnam at 60K:1 (though I don't recall if this was infantry or overall, or small arms ammo or what.)

I've noticed a distinct snap when reseating bullets that I loaded as little as a week prior. I've also noticed a lack of that snap when reseating stuff I loaded over a year ago. I have no idea why, but have never noticed a verifiable difference at the range.