How quickly do bullets "weld" to the neck?

[Downhill]

I have posted this in another thread. Decades ago an old BR shooter told me to coat steel BB's in graphite and swirl your bullet in a container of such before seating. Does it help? Don't know. Does it hurt? Probably not. It has just become second nature when seating bullets. I have some Lake City 69 M2 Ball that I have tried seating the bullet a hair deeper in, there is an audible "crack" when doing so. Cold welded, maybe. Cold war sealant, maybe,Don't really know. Will still win a M1 Match.

 

[gunsandgunsmithing]

Thank you Sir
Have not heard of that type of coating. Just started in last 6 months or so using bushing dyes and mandrels ,but dipping the bullet in graphite before seating. I do not know if that prevents the cold weld conspiracy, however I would be inclined to think something between the case and projectile would have to be of some benefit.
Lots of theories about yes cold weld is or isn't a thing, not much being said about how to stop it if so inclined.

Everyone have a great day.

I'm not concerned about what others think in terms of "if" it happens. I'll trust what I've seen and just be happy with my own conclusions about it.

That said, I think anything that is hygroscopic, even a thin layer between the bullet and the case neck, has the potential to introduce moisture at that interface, where there happens to be carbon and other remnants from combustion that when have moisture introduced, creates an acidic mix that creates oxidation. I think this is what most are calling bullet weld..or whatever you want to call it.

Bottom line, I'm not sure if that coating makes things better in regard to oxidation, or worse, but I suspect it may actually worsen or hasten oxidation where the bullet and neck are in contact. Who knows. Just my 2 cents is all.

 

[Link]

Some folks have waaaaay too much time on their hands.

Did you read all 130 posts? ;]

 

[miningshawn]

Did you read all 130 posts? ;]

As the OP of this thread, yes I did. I am going to change my habits a little.

I live in Montana, and I like to reload in large batches to maximize my range time in good weather. A couple of things that work for me - I have naturally low humidity, and my reloading happens indoors under temperature control because the garage and outbuildings are not heated.

I clean my brass using two methods. For the first few cycles I tumble with media. I also have a sonic cleaner that I use after 5 or so loads to recapture the "shine" and clean the inner cartridge base. My instances of cold welding have happened after loading new brass or after loading sonic-cleaned cases.

I believe that the carbon left in the necks after firing aids in reduction of cold welding. Whether you believe that or not is irrelevant to me. When I load new or sonic-cleaned the seating pressure is almost always higher than fired and tumbled.

As a rule I form habits that promote consistency. Starting this year I will be tumbling everything before sizing. After I size and prime I will be using a container with BB's and graphite and dipping/swirling each neck. I tried it over the course of this thread and it has not reduced my seating force; BUT, it has averaged (weighted mean) it.

I am very hesitant to use a liquid, paste, or non-carbon based lubricant for seating. It is messy, and provides a catalyst for ion-transfer between surfaces - something that carbon doesn't.

I want to thank everyone that chimed in, even the trolls. This thread is actually fairly comprehensive and the first long discussion of it's kind that I have found. The thread should allow a free-thinking reloader to adjust reloading habits or ignore cold welding as they see fit.

Thanks all!
Shawn

 

[Andy Work]

I asked a ballistic tech about this:

The subject of "cold welding" keeps coming up on the interwebs. I know that a lot of shooters will seat long then seat to desired length the day of the match. I've seen the videos of guys reseating bullets that have been loaded for a while and get a pop sound when it moves. Has there been any scientific study on this?

Yes, the bullet jacket material and the brass case have a similar molecular construction, so they tend to bond over time. That bond creates more neck tension, and will ultimately raise pressure, creating a different vibration pattern from the barrel, creating a difference in where that projectile will impact. Breaking the bond doesn’t bring the neck tension back to what it was on day one, but it doesn’t hurt.

Is there a recommended coating, lube or pixie dust to prevent this?

No, adding a lube or wax will reduce the neck tension and change the dynamics of the ammo and how it works from the firearm. You can test that with a new run of ten or so shots with lube included.

The best advice I can give is to test a theory. If you have any ammo that is more than a few years old, shoot it side by side against a new batch made the same way and test for accuracy. If you see no change, continue shooting the older ammo until it runs out. If you do see a change, take another five or so of the old ammo and break the bond as discussed and test them for accuracy. If the accuracy returns, then the rest need the same treatment.

 

[101stjetmech]

I ran a small test on the effects of reseating bullets just prior to shooting, but did it a bit different than other's I've seen. I did it by measuring the force required to pull the bullet using a collet puller and a spring scale.

20 Remington 30-06 cases were prepped for loading as usual, cases resized with lanolin to include inside the neck, cases then cleaned in walnut media with a bit of mineral spirits and NuFinish. No primers or powder, Sierra 168s seated.

The 20 were left overnight. The next day, using an RCBS collet puller in the Rockchuker, 10 bullets were pulled using a calibrated spring scale midpoint on the press handle. Readings recorded varied between 4 to 12 pounds of force needed to pull the bullets.

The next 10 then had the bullets seated about .010" deeper and immediately pulled. These 10 had a much narrower range of pull force needed, running 4 to 6 pounds max.

Although a very small test, it does indicate that some form "cold welding" does occur.

 

[DiRTY DOG]

Although a very small test, it does indicate that some form "cold welding" does occur.

Are you sure that's the ONLY conclusion possible from your test? That as much as 6 additional pounds of "cold weld" happened overnight?

How do you know it's not something else like brass spring back? Seating bullets stretches the case mouth. The amount of stretch is determined by how much interference you set.

Bullets that were seated only for a few minutes or less and then immediately pulled likely had less brass spring back and therefore less force required to pull them.

Bullets that were seated and pulled the next day had much more time to spring back, causing more force to pull them.

Also you didn't mention brass condition, were they annealed? Were they all previously fired the same number of times?

 

[gunsandgunsmithing]

Are you sure that's the ONLY conclusion possible from your test? That as much as 6 additional pounds of "cold weld" happened overnight?

How do you know it's not something else like brass spring back? Seating bullets stretches the case mouth. The amount of stretch is determined by how much interference you set.

Bullets that were seated only for a few minutes or less and then immediately pulled likely had less brass spring back and therefore less force required to pull them.

Bullets that were seated and pulled the next day had much more time to spring back, causing more force to pull them.

Also you didn't mention brass condition, were they annealed? Were they all previously fired the same number of times?

I've noticed a difference in seating pressure with brass that was sized a day or three ago vs that sized just before charging a seating a bullet. I think that'd be a simple test worth doing...fwiw.

 

[Bottom Fodder]

I prep my brass shortly after its fire doing everything except run a mandrel in the neck I wait until I’m ready to reload it Normal a day or so before I plan to shoot. Not sure if that has any or no affect but that is my routine

 

[ebb]

When the cold weld is broken by the gun being fired, do pieces of the neck stick to the bullet or do pieces of the bullet stick to the neck? I guess you could also ask if any transfer of material is made at all. The only welds that I have experience with are welding to identical metals to each other either with a filler rod or without (like a spot welder) with that type the broken weld is never perfect one or the other pieces has material transferred. I have no idea if that happens here but if it did then that could explain why some see accuracy diminished.

 

[ronemus]

Only points of contact can bond (a better term for what's happening than weld). Case necks are usually moderately rough inside as produced and after firing. Unless you polish the inside of the case necks, only a small percentage of the surface can bond and the pressure of firing will peel the neck from the bullet. it is unlikely that there will be much material transfer. The gilding metal used for bullets and the brass used for cases are comparable in hardness, so the effects would be minimal and much less severe than the engraving force when the bullet enters the rifling. In the extreme case where the bullet and case neck are highly polished and free of oxidation, oils, lubricants, etc., it is possible that the bond would cover most of the area where the bullet is in the neck and the neck could be pulled off the case and head down the barrel with severe consequences; however, that would be very unlikely with normal loading practices.