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

[jimbires]

good thread guys . I've just been reading trying to learn something about this . I'll share my story now . 6 or 8 years ago I bought a new bag of rem brass for my 7mm rem mag . on the second fire the case neck would be broken off left in the chamber . all I had to do was tip the barrel up and the neck would fall out . I decided to junk the brass so a year or so goes by and I decided to pull the bullets and save what I could . this was the first time I ever seen this corrosion or welding . I was using a standard rcbs die with the expander ball . at that time I was using hornady one shot lube , I've stopped using it now . these were loaded with rl22 powder and hornady sst bullets . I have no idea what my neck tension was , sorry . I don't wear gloves while I load , and I do sweat easily , I have often thought about this being my problem . here are a few pics I have .

don't get excited about the cases being bent up at the bottom , there not . it's a reflection from the hex holes in the loading tray . these are ones that broke off on the second shot . these were only loaded for a few days before I fired them .

this photo shows the corrosion or weld were talking about .

 

[jlow]

I may be wrong but I don’t think cold welding in the true sense have anything to do with corrosion. Cold welding is supposedly the fusing of two metals under high pressure, absence of air, and at room temperature?

 

[johara1]

Wayne, Maybe the DTAC's don't stick or maybe that stuff on your boots is get in the mix.......... jim

 

[bozo699]

Wayne, Maybe the DTAC's don't stick or maybe that stuff on your boots is get in the mix.......... jim

;D ;D ;D You may have something there Jim
Wayne.

 

[bozo699]

I may be wrong but I don’t think cold welding in the true sense have anything to do with corrosion. Cold welding is supposedly the fusing of two metals under high pressure, absence of air, and at room temperature?

jlow,
I believe you are correct, I read somewhere that it took several hundred thousand psi to cold weld and of course you won't get that with .001 neck tension will you?....NO! I believe it is a case of bad terminology, we say jamming the bullets when actually were just touching the lands or are .010 into the lands but as a reloader your perfectly aware that that isn't the true meaning of Jam is it?...NO! so I think we can safely say were using cold welded as a lack of a better term or the lack of knowledge of the correct terminology THE GALL DARN BULLET IS STUCK AND POPS WHEN SEATED FURTHER!!! ;D
Wayne.

 

[jlow]

Here is an interesting read on “cold welding”:

http://www.coldpressurewelding.com/cms/index.php?option=com_content&view=article&id=92&Itemid=2&lang=en

I think pressure is only one factor; the other is how close the two surfaces can come in contact with each other allowing interaction of electrons and atoms between the two surfaces. I think this where smooth clean surfaces that are pressed in close contact plays a role.

 

[TC260]

I read somewhere that it took several hundred thousand psi to cold weld and of course you won't get that with .001 neck tension will you?....NO! I believe it is a case of bad terminology

I understand what you're saying. It's true we're not getting a permanent "cold weld" in the sense that the bullet and case are permantently fused together like they would in a machine. We don't have anywhere near the pressure (among other things) to make that happen. That doesn't mean though that their can't be a partial cold weld situation happening. Here's what I mean.

Copper, whether it's in the jacket or in the brass, is nothing more than trillions of copper atoms. If those atoms come in close enough contact to each other they can exchange electrons and form a metallic bond with each other. When the two materials are pressed together at extremely high pressure, let's say for the sake of the argument, 100% of the atoms on both sides come in contact with each other and bond. In that case there's a permanent, unbreakable bond between each parent material.

What happens if there's some contamination between the two parent materials and say 75% of those atoms bond with each other? The joint between the two materials is going to be a little weaker. What if there's less pressure and only 50% of the atoms bond? You can see where I'm going with this. In the case of the bullet, maybe there's only 1% of the copper atoms bonded. In which case the overall force required to break the bullet free from the case is relatively small but the noneless, those copper atoms that were bonded were cold welded together even if there wasn't a high enough percentage of them bonded to permanently join the two pieces.

Again, I'm not stating this IS what's going on. I honestly don't know. Just stating a plausible explanation for how we could still be seeing cold welding even though there isn't a permanent bond between the bullet and the case.

 

[bozo699]

I read somewhere that it took several hundred thousand psi to cold weld and of course you won't get that with .001 neck tension will you?....NO! I believe it is a case of bad terminology

I understand what you're saying. It's true we're not getting a permanent "cold weld" in the sense that the bullet and case are permantently fused together like they would in a machine. We don't have anywhere near the pressure (among other things) to make that happen. That doesn't mean though that their can't be a partial cold weld situation happening. Here's what I mean.

Copper, whether it's in the jacket or in the brass, is nothing more than trillions of copper atoms. If those atoms come in close enough contact to each other they can exchange electrons and form a metallic bond with each other. When the two materials are pressed together at extremely high pressure, let's say for the sake of the argument, 100% of the atoms on both sides come in contact with each other and bond. In that case there's a permanent, unbreakable bond between each parent material.

What happens if there's some contamination between the two parent materials and say 75% of those atoms bond with each other? The joint between the two materials is going to be a little weaker. What if there's less pressure and only 50% of the atoms bond? You can see where I'm going with this. In the case of the bullet, maybe there's only 1% of the copper atoms bonded. In which case the overall force required to break the bullet free from the case is relatively small but the noneless, those copper atoms that were bonded were cold welded together even if there wasn't a high enough percentage of them bonded to permanently join the two pieces.

Again, I'm not stating this IS what's going on. I honestly don't know. Just stating a plausible explanation for how we could still be seeing cold welding even though there isn't a permanent bond between the bullet and the case.

TC260,
Welcome to the forum,...from your first two posts you look like you will be a real asset to this forum and it's members. I also don't know what is going on but I do know for sure something is as too many of us has experienced these problems, very well thought out post my friend, I will be looking for more of your posts.
Wayne.

 

[jlow]

There can never be 100% bonding between the neck and the bullet since for that to happen; the two surfaces will have to be 100% smooth for the complete surface to mate 100%. If you look at the two surfaces with an electron microscope, it would look like the Grand Canyon with huge peaks and valleys and only the top of the peaks will be available for contact between the two sides. This is likely the reason why in the case of cold welding, one can feel a certain degree of welding but that it is still “breakable” using the press. Contaminants on either or both surfaces will further reduce the likelihood of a cold weld.

 

[bozo699]

Boyd,
You sure have got some mileage out of this one, not really what you were looking for but mileage never the less
Wayne.

 

[BoydAllen]

Now we are starting to get close to what I have been thinking.

 

[BoydAllen]

I am really proud of all of the responders to my request. We have all remained civil, and I believe that some learning has taken place. It doesn't get much better, on an internet forum. Thanks to everyone.

 

[Nodak7mm]

I am really proud of all of the responders to my request. We have all remained civil, and I believe that some learning has taken place. It doesn't get much better, on an internet forum. Thanks to everyone.

Boyd, See what happens when you let the love flow.......... ;D

Ok, on a serious note, this discussion now begs the question; Methods to prevent this phenomenon??

Rod

 

[jlow]

Yes, threads are most productive if folks focus on the questions and solution and avoid anything personal.

As for prevention, I think the idea of a contaminant to block cold welding is the best I have seen to prevent this. From what I can see, the two welding surface has to be absolutely clean so one of the neck lubricants would be my best bet as it would serve duel purpose.

 

[BoydAllen]

Perhaps painting the inside of case necks with nitrocellulose lacquer, an letting it dry before seating bullets? If it would survive bullet seating, with perhaps a thin coating of wax on the bullet......Just a thought

 

[Nodak7mm]

Adding another thought...... Does moly prevent this? Maybe another reason to look again at molying bullets?

Jlow, agreed and this site is one of the best in my opinion for proof that folks can be professional & communicate in good manner . I tend to get immature ;D , but only in a fun intent...

Good thread Boyd!!

Rod

 

[BoydAllen]

Actually, I have heard that moly can make the situation worse, but I should qualify that by saying that I don't know if the bullets involved had been waxed, as per the original NECO procedure.

 

[bozo699]

Actually, I have heard that moly can make the situation worse, but I should qualify that by saying that I don't know if the bullets involved had been waxed, as per the original NECO procedure.

Boyd,
I meant to talk to you about that on the phone and as per usual we got off on something else and I forgot. On the 6*284's I seated long for the Deep Creek match last year and seated them back just before the match were mollied but was NOT WAXED!! The moly was applied in a vibratory with ceramic beads and moly was purchased @ Sinclairs, can't think of anything else to add that I haven't told you on the phone or this post but if there is ask away
Wayne.

 

[BoydAllen]

Were those the ones that we discussed, where some of them were "cold welded" to the point that you could hardly break them free with a Sinclair arbor press ? If memory serves you had steel wooled the inside of the necks after annealing, and seated the bullets only a few days before the match? Sort of a perfect storm.....

 

[bozo699]

Were those the ones that we discussed, where some of them were "cold welded" to the point that you could hardly break them free with a Sinclair arbor press ? If memory serves you had steel wooled the inside of the necks after annealing, and seated the bullets only a few days before the match? Sort of a perfect storm.....

Live and learn they say ;D
Wayne.

Oh yea those were the ones.