Cold welding of bullets in case necks and moly coated bullets

[swd]

NASA developed Teflon as an intervening coating or mechanical device to prevent a process known as vacuum welding. Though different in nature, it achieves bonds very similar to what we see between bullets and case necks.

Teflon was invented by accident in the late 1930's by a chemist trying to invent a new refrigerant gas about 20 years before NASA even existed. I'm sure NASA found plenty of good uses for it later on. One of it's early very important uses was in the Manhattan Project for enriching uranium for the bomb.

 

[JarheadAZ]

swd and LHSmith;

Thank you for the Teflon info, its always good to learn more than I already thought I knew. The only bad day is a day when I don't learn something new.

Maybe I'm over-cleaning my brass if carbon in the case necks is a positive factor. This makes me wonder whether my antipathy toward carbon coating in the case interior is negative, positive, or neutral toward accuracy.

Greg

 

[BoydAllen]

All the short range benchrest shooters that I know do not clean the inside of their case necks beyond running a brush in and out a couple of times. One Hall of Fame member that I know does not clean them at all, because he once did a test, the results of which favored that approach. Long range requires attention to whatever details affect ES of velocities, so the requirements as far as the inside of the case body may be different. The problem is that if one cleans the inside of the case, carbon in the neck will be removed as well. If ammo is shot reasonably close to the time that it is loaded, and the seating forces are relatively uniform, then I would imagine that there would be little harm, but that is beyond my actual experience since I do not load for those events.

 

[AckleymanII]

I lived out West for 30 years, then moved back home in the South. I never saw "welding" until I moved South where the humidity is so high. I have seen it three different times in a few years.

I can say that I don't understand it, and it does spook me due to the possibility of sky high pressures.

I remember that PMC coated the inside of their necks with some Black Lucas liquid for a reason that they did not disclose when they were manufacturing ammo in Henderson, Nv. I have no idea what Black Lucas is.

 

[BoydAllen]

They may have been coating the inside of their case necks with some sort of asphalt based coating, similar to what the military has used. My search came up with Lucas being a company that makes coatings for the roofing industry, including products that have an asphalt base. If you look down this search results page to the seventh item, you will see that a company by the name of Hernon makes a product that is asphalt based that seems to be just for coating the inside of case necks . I have no idea what it does to accuracy, or if it results in any barrel fouling.

 

[M14AMU]

In all the years I shot NRA HP.....I would sometimes load 300-400 rounds possibly a month prior to a major event I was going to shoot! I NEVER seated the bullets in the cases to my desired finished length; rather I loaded all rounds .020" long and at the match before going on line I would seat to my desired length with a Wilson Inline Seating Tool!

 

[gitano]

There have been great wrongs perpetrated in the name of "science" when someone takes genuine field observations from one locale, develops a "generalized theory" from that locale-specific data, and applied that theory across the world. That's the view I have of this "Cold Welding" issue.

I have NO DOUBT that reasonable people have observed some irrefutable examples of bullets 'sticking' to case necks. I am equally certain that many of us have experiences that refute a generalized application of a locale-specific phenomenon - "cold welding" of bullets to case necks.

Personally, I think that Ackleyman II has made "the point". Namely, it is 'impossible' to get dielectricly-induced bonding, without moisture present. For those that live in climes where humidity is high, (and remember that humidity is usually reported as RELATIVE humidity), I think "cold welding" is "real". To those that live in an area where humidity is a "non-issue", bullets bonding to case necks is non-existent.

Of course I cannot prove the above assumption, BUT, here is what IS indisputable:

Reasonable and reliable people have observed bullet-to-case bonding as a function of time.
Reasonable and reliable people have never observed bullet-to-case bonding over over intervals of time that are tens of times longer than that observed in cases where bullets did bond to cases.

The real world is rarely "yes" OR "no". Usually it's just "uh huh".

Paul

 

[Brians356]

"Cold Fusion" was debunked 25 years ago. Careers were ruined. Reputations were besmirched. Don't risk yours by embracing it now.

 

[M14AMU]

"Cold Fusion" was debunked 25 years ago. Careers were ruined. Reputations were besmirched. Don't risk yours by embracing it now.

Keep on believing that!

 

[jsthntn247]

"Cold Fusion" was debunked 25 years ago. Careers were ruined. Reputations were besmirched. Don't risk yours by embracing it now.

I made a video a while back of bullets taking over 100lbs (30lbs initially) of seating force to seat deeper in the case and a loud pop when they started to move.

 

[BoydAllen]

Some time ago, in a thread that I had started about the same topic, I was treated to responses by fellows who had no experience with the phenomenon, and whose answers indicated that they had serious doubts as to is reality. Those of us who have seen this have some basis upon which to base conjecture about how it happens. Now as then, those who have not are probably just muddying up the water.

As to the reasons that very old ammo might not show this, the only thing that comes to mind would be the possibility that the inside of case necks might have been coated with something that prevented it. Beyond that, I have no clue.

Generally, I think that experience supports either loading a short time before use, or loading long, and seating to final depth just before use. A friend who loads and lays away some ammo for his wildcat caliber hunting rifles, uses his fingers to apply wax to bullets just before he seats them , and has reported that he has had no issues with cold welding or accuracy.

 

[Brians356]

I made a video a while back of bullets taking over 100lbs (30lbs initially) of seating force to seat deeper in the case and a loud pop when they started to move.

Would a typical plastic inertial bullet puller have dislodged those bullets?

 

[M14AMU]

Amazing, the amount of information one can uncover with a bit of research beyond the unreliable Wikipedia.

"One of the first requisites for service ammunition is that it shall be waterproof". The primers are sealed and the case is treated internally with a waterproofing sealant. That sealant is probably the reason old surplus military ammo is shootable to this day. Commercial ammo isn't sealed, nor is the ammo we hand load, creating the bond between the brass and copper over a period of time due to corrosion from moisture and air.

When we had to shoot BALL AMMO in 7.62MM for Leg Matches instead of LC or FA Match ammo....many of us took that stuff before the match and broke the seal with inline seaters before shooting! Shot pretty good after that...but it was STUCK bigtime prior to breaking the seal!!

 

[snowpro440]

I remember getting a load of .50 cal. ammo that was manufactured in the late 40"s an 50"s to haul to a reclamation center that was stored in the bunker in wooden crates that when opened it looked as close to new as I have seen , so that being said , I believe it's all in how you store the ammo .

 

[BoydAllen]

There is no visible evidence of "cold welding". You only know that it has happened when you try to seat a bullet a little deeper. In the cases where I have personally seen it, the ammo was stored in the house. I live in Fresno, CA, which is not as dry as some places, but far from humid.

 

[Brians356]

Boyd,

I'll repeat an earlier question (to date unanswered): Would a typical plastic inertial bullet puller have dislodged those bullets?

(I know "it depends", but at least WRT the ones you experienced?)

 

[jsthntn247]

Boyd,

I'll repeat an earlier question (to date unanswered): Would a typical plastic inertial bullet puller have dislodged those bullets?

(I know "it depends", but at least WRT the ones you experienced?)

Yea Doubting Thomas a inertia bullet puller will dislodge them. However, some bullets take 4 hits on a concrete floor and some take 44. No discernable difference at the time loaded, just when shot or tried to pull months or weeks later.

 

[savagedasher]

;D It's all about how you swing the hammer. I helped a friend who was a carpenter he would drive a nail with three hits . Mine was 5 or more. ;D
Bullets do cold bond. Lube can also make a bullet harder to move . Perfect surface.
Larry

 

[Heavy barrel]

I have had this happen to me before. I had some I loaded for a rifle but didn't shoot them. About a year later I bought a new rifle and figured I would shoot them. The bolt would not close on them. The throat was shorter in the new rifle. I seated them deeper & they made a loud pop & then moved smoothly. These where bare Lapua bullets in Lapua brass. The brass might have been new but I can't say for sure. This was several years ago. I live in AZ so high humidity is not the problem.

 

[Heavy barrel]

The "pop" is the sound created by the vacuum in the case when the seal between bullet and case separates.

And the extra force it takes to get it to pop is caused by?