Bullets "cold welding" to cases

[Laelkhunter]

I just read in another thread about someone using some LU204 Dry Graphite Lube lube on the inside of the case neck and mouth to prevent "cold welding" of the bullet to the case.

Five questions:

1- Is this really a problem that you have to "lube" the neck to prevent cold welding
2- Has anyone really experienced cold weld
3- How long does it take to occur (if at all)
4- How does it affect the cartridge (if at all-pressure, accuracy, etc).
5- Does it occur in reloads or factory (seems factory sits on the shelf awhile)
And I will repeat #2, has anyone really experienced it?

I have never heard anything about it before reading it on this Forum, and have been shooting about 50 years, and reloading about 45 years. Having shot in competition many years, and having been to two Military Sniper schools for the PD, I have never heard of bullets "cold welding" to the case.

 

[gohring3006]

If you don't shoot over 500 yards it's not a problem.
When you stretch it out, the extreme spread starts getting bigger, and you will see fliers and some vertical dispersion.

 

[elkaholic]

It does happen and does affect accuracy and pressure, but usually, as gohring said, mostly at longer ranges. I did hear recently that, since HBN treatments have emerged, there is some kind of reaction taking place that can stick the bullet so tightly that the bullets were damaged when trying to remove them. Ya I know, HBN is supposed to do the opposite! I think this might be when something more than HBN is present in the case mouth, but I can't remember which forum member had this happen? Maybe they will read this and chime in......Rich

 

[Laelkhunter]

Thanks. I guess it's kinda like worrying about temperature sensitive powders, if you don't shoot at long range (less than 300 or 400 yards), it shouldn't have an affect on hunting accuracy ?

 

[jimbires]

I dip my bullet base in dry powder graphite before seating . I think this will help with this cold weld , or what ever it is that happens . I think I did have this happen . I had some ammo loaded that I wanted to pull apart because I was having brass falure issues . it must have been brittle brass . on the second fire a few of the necks were coming off in the rifle . I'd have to tip the rifle up to get the neck to fall out of the chamber . when I got around to pulling the bullets I had 2 that the necks were stuck to the bullet tight enough they pulled the neck off the brass case. you can see corrosion around the bullet base . I have no answer for this , but I don't think I've had any problems since . when I hear of this cold weld I wonder if it's this corrision issue I had .

 

[elkaholic]

I think it is corrosion, or at least chemical reaction. I think the guy who told me about his experience, that I mentioned above, said it was cases that were not cleaned prior to HBN and had carbon in the neck from firing......Rich

 

[Barrelnut]

Have not seen any real issues with it, especially like Jimbire's above, but I believe it is called bi metal corrosion. This is why you have to use Never Seize when putting stainless barrels on chromoly actions.

I think I have seen it on old factory ammo, so old that the bullets have tarnished or oxodised some. You see that green ring around the bullet and brass at the cantalure.

I have seen green corrosion inside cartridge necks when brass has set for long periods of time without the necks being cleaned and have powder soot in them. I think there is still some slightly corrosive substances in primers and powder that can cause this over time, if not removed.

 

[ShtrRdy]

Dang! I never heard of this. Thanks for the pictures jimbries.

 

[Gene]

I have experienced cold welding when pulling bullets from old military brass, mostly. Not with older stuff have I reloaded.

I would never lube a bullet or inside the case neck to make seating easier. I always lube inside neck before expanding, but then remove it with Q tip. I want consistent release with each bullet I fire.

 

[hemiford]

I still question this.
Corrosion is not welding.
"Glueing/sticking" is not welding, but it would be bad, of course.

 

[Wedgy]

I just posted this on the other thread;

Differing metals corrode when they're electrochemically dissimilar...the rate of corrosion is based on the difference in their anodic index...and the metal with the higher index is the one corroded. Copper and brass have very similar V's (given brass is 60-70% copper depending on alloy) so it's very slow to occur.
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The binding has the effect of different neck tension, a LOT more. The longer the range the more you will see its effect. Seems that SS pins and ultrasonic cleaning can clean the necks free of carbon which can allow the brass to bond to the copper faster, though it still takes months.
Lots to read
http://www.longrangehunting.com/forums/f28/can-inside-necks-clean-184134/

hBN bore treatment?

 

[Laelkhunter]

Thanks Wedgy, that's the one I saw too, but didn't know how to link it to here.

 

[ohiohunter]

No need to be so literal gene, we didn't invent the expression. Kind of like who ****ed in your wheaties?... an expression, nothing more.



Regardless of the rate I know several f-class guys that insist on loading long and seating their bullets the night before a match to reduce time/exposure to cold weld. I think it was BignGreen who said he dry lubes his BR loads. Personally if I'm going to make a batch of bullets that may take a few yrs to shoot I certainly lube them.


The lube isn't so they seat easier, its so they release more consistently or more uniform neck tension. Seating doesn't get much easier when you're running 1-2 thousands neck tension.

 

[Jud96]

I recently experienced this phenomenon when my Dad was pulling apart some old .222 Rem shells that he loaded 20+ years ago. Just by using an RCBS bullet puller, it was tearing the necks off with the bullets still inside of them. These did not have excessive neck tension and no sort of coatings were applied to the bullets. Our thoughts were maybe the brass just got brittle over time or corrosion formed between the case neck and bullet. I have never seen it occur anytime before or after this, may have just been an odd occurrence. There was no real sign of corrosion near the case mouth such as green or crusty stuff, but the cases and bullets were tarnished.