Bullet weld and pressure relationship

[wboggs]

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 have seen it with some Rem factory loads with SwiftAFrame that were about 20 years old and stored in controlled conditions after I bought them retail. Would get an occasional flier but no pressure signs. Pulled them and found corrosion in the bullet/neck. Put in a seater and seat them deeper and they pull easier.

 

[6Creed73]

For those using neolube. At which point do you lube the necks? I presume it is after powder drop just before bullet seating?

Before powder drop, prior to mandrel and bullet seating in my case. It dries very quickly, so no risk of powder sticking after it's been lubed.

 

[asquared19]

Before powder drop, prior to mandrel and bullet seating in my case. It dries very quickly, so no risk of powder sticking after it's been lubed.

Noted. In my current setup for rifle I use the Lee powder drum drop initial charge, weigh, and trickle to final desired load. My thinking on powder prior to neolube is that I don't want the charge drop with the Lee auto drum to scrape any of the neolube off.

Thoughts?

 

[6Creed73]

Noted. In my current setup for rifle I use the Lee powder drum drop initial charge, weigh, and trickle to final desired load. My thinking on powder prior to neolube is that I don't want the charge drop with the Lee auto drum to scrape any of the neolube off.

Thoughts?

I'm not familiar with the Lee auto drum, but I can tell you that even running a mandrel through the neck doesn't remove the neolube.

What I do is apply neolube with a q-tip, let it dry, run the mandrel through the neck, drop charge, and seat bullet. In my process the neolube is still on the neck at the bullet seating step.

 

[Webster]

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 wish someone on this website could do surface analysis on a sample to finally determine what the black material is composed of. We need to put an end to what the deposit is. It must be some type of corrosion maybe created by decomposition of the powder or moisture? If it was corrosion, I would think you would see more of it on the bullet?

What can XPS Analysis tell us about a sample?
X-ray photoelectron spectroscopy (XPS), also known as electron spectroscopy for chemical analysis (ESCA), is a technique for analyzing a material's surface chemistry. XPS can measure elemental composition as well as the chemical and electronic state of the atoms within a material.

 

[RegionRat]

Are you asking about a sample of neck residue from firing?

Or a sample of the corrosion found when bullets stick to case necks?

What can XPS Analysis tell us about a sample?

We can't detect hydrogen in SEM XPS, so it isn't very good at hydrocarbons (organics) unless all you want to know is the binding energy of other elements.
We typically use a battery of tests to understand complex forensics, and SEM is just one of them.

There ain't much that hasn't already been looked at many times over, but I'm not clear on what sample you want to learn about?

 

[Webster]

Are you asking about a sample of neck residue from firing?

Or a sample of the corrosion found when bullets stick to case necks?

We can't detect hydrogen in SEM XPS, so it isn't very good at hydrocarbons (organics) unless all you want to know is the binding energy of other elements.
We typically use a battery of tests to understand complex forensics, and SEM is just one of them.

There ain't much that hasn't already been looked at many times over, but I'm not clear on what sample you want to learn about?

The black deposit on a bullet that was cold welded to the neck. Any analysis data would be informative. If the deposit contained Cu and or Zn it would indicate corrosion. I was not involved with these types of analysis but it was done in my Dept. Electrospray Mass Spec Chromatography would ID organics from gun powder additives or lube put on the necks.

 

[Phys86]

Is there any updates on this?

What do commerical ammunition manufacturers like Hornady do? Apply something to the bullet or case neck?

 

[Webster]

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

If I wasn't retired I would have liked to analyze any discolored area on the bullet. It must be some kind of corrosion caused by the weird chemicals in smokeless powder. Some degree of moisture should also be present for corrosion to form. If someone out there is a SEM operator could you do the simple analysis. This problem has been talked about for years and it should be simple to learn more. I don't know how you could prevent it. Does it only occur with certain powders? Does it matter if it's single or double base powder?

Possibly reloading with the so called carbon residue in the neck i.d. is a problem. Some guys think the black residue is a good lube for seating bullets. I'm sure it isn't just carbon but a mixture of many chemicals. Might be a good idea to spin a bronze or nylon brush in each neck to clean it up.

 

[jds holler]

This will turn you into a worrywart when it comes to removing the copper from your barrel at the very least. And it may explain the "neck weld" that occurs between a brass case and a copper bullet jacket.

Electrolytic Corrosion (Electrolysis) occurs when dissimilar metals are in contact in the presence of an electrolyte, such as water (moisture) containing very small amounts of acid. The dissimilar metals set up a galvanic action which results in the deterioration of one of them. The following is a list of the more common commercial metals, sequenced according to what is known as the "Galvanic Table":
THE GALVANIC TABLE

1. Aluminum
2. Zinc
3. Steel
4. Iron
5. Nickel
6. Stainless Steel Series 400
7. Tin
8. Lead
9. Brass
10. Copper
11. Bronze
12. Stainless Steel Series 300

When any two metals in the “Galvanic Table” above are in contact, with an electrolytic present, the one with the lower number is corroded. The galvanic action increases as the metals are farther apart in the Galvanic Series. It is not always true that there is greater corrosion the further down the scale one goes. In certain cases one metal immediately following another may be very corrosive.
One of the most important facts that one should know about a metal or an alloy is its reaction with other metals or alloys with which it may be in contact. This data is given in the Galvanic Table. Here the metals are listed in a sequence in which each metal is corroded by all that follow it. In other words, when two different metals are in contact with each other in the presence of moisture, there will be a flow of current from one metal (the “anode”) to the other metal (the “cathode”), and one will be eaten away, or disintegrated, while the other (the “cathode”) will remain intact.
An important point to remember in utilizing the Galvanic Series is that moisture is the chief problem in this type of corrosion, and moisture depends a great deal upon climate. In the desert, electrochemical action will be at a minimum. On the seacoast the action will be much greater, not only because of the ever-present moisture, but also because of the salt. Some means of separating dissimilar metals must therefore always be found.
In any galvanic combination, the relative areas of the two materials forming the couple have a very important bearing on the extent of the corrosion. Under many conditions the extent of galvanic effect will be directly proportional to the ratio of the area of the metal lower in the list. Thus, if a piece of steel having a surface area of two square inches is coupled to a piece of copper having a surface area of 100 square inches, the galvanic corrosion is roughly 50 times faster than it would be if the same piece of steel were coupled to a piece of copper having a surface area of two square inches.
For this reason, it is wise to avoid galvanic couples where the exposed area of the metal lower in the galvanic series is much greater than that of the metal high in this series. As a practical example, it would definitely be dangerous to use a steel rivet to a copper plate, but reasonably safe to use a copper rivet to a steel plate.

 

[searcher]

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?

Oh - but it does....
I'm sure it most often is associated with storage conditions, as I've bought lots of surplus ammo I used to buy in crates which I believe to have been from WWII and Korean War eras. Back in the late 70's and into the 80's, that stuff was all over the place. Even in the vacuum sealed bags, a lot of it was trash, so welded to the cases, I can't even imagine shooting it. Some of it was pristine in comparison - like it was only a few years old. I went to pull bullets in some factory .375 H&H Winchester ammo a while back (I bought about 20 years ago new) and those bullets were stuck so tight, I thought I was going to rip the necks off. The ammo had sat on a shelf in my insulated shop which never goes above mid 70's and never below 50 degrees, and I don't live in a humid climate. The conditions were enough, however, to definitely cause considerable cold welding. Would they have shot O.K.? Maybe. But most folks don't try to pull bullets on old factory ammo to see that the cold weld is there. If that ammo wasn't sealed up - the cold weld is there in some degree, almost certainly.

Just last week, I went to the range and decided to "shoot up" some older .223 varmint ammo I had loaded up about 5 years ago. Neary all of it was moly coated, though I had one box that had bare bullets. They were all loaded the same date, with same load, powder, bullet and primers - only difference was the moly on most of them - which is something I have done for a long time with ammo intended for potential long-term storage - just in case they didn't get used as fast as I anticipate. I've never had ammo shoot bad that was moly coated after sitting around for a long time. The box of ammo (50) that was bare resulted in the creation of circular cracks in the brass in about 30 of the 50 rounds, right where the base of the bullet sat. I didn't notice the fine cracks in the brass until I got home that evening, after tumbling the brass. I did know that my "pet load" shot like crap with that box of bullets, yet the moly coated bullets shot fine. There was not a single split neck. There were no such cracks on the moly coated ammo. Looking at my notes on each box, all the brass had been annealed prior to loading, was all the same batch of Lake City brass, fired the same number of times, etc. No processes involving water were used on any of it. I have never encountered anything like that with handloaded ammo in 50+ years. I came to the conclusion that the cold welding was bad enough for the bullet to want to take the neck with it. Yikes! So now, I'm going to go through my inventory of ammo and check it all. There is obviously enough moisture in my shop to cause more problems than I would have thought possible.

 

[Doom]

The bullet shows no sign of cold welding. The black is most probably graphite from the Neolube.

 

[joshb]

I did some searching and found this info. Seems the Military uses a “waterproofing “ compound in the neck of the case. Maybe it’s their answer to bullet weld? Here’s the info I found:

 

[Phys86]

I had some cold welding in some 243 rounds I loaded in September. I took them out of storage yesterday and screwed the seater in a couple thousandths. Then gently raises the ram and "pop". Every one out of about 20 popped.

These were on their 3rd loading, I think. Neck carbon had not been removed, but had been annealed every time and then brushed with a nylon brush. I can't remember if I used imperial graphite lube or not