Home Forums Hunting & Shooting Ask The Gunwriters Weld bonding

I've been reading about this in my spare time for a couple days! I believe it caused by case necks being undersized for the bullet. Along with case shrink over time! Since new brass seems to be resistant,annealed brass is more resistant, than used not annealed brass! Dirt and residue acts like a release agent. Bench rest shooters have many theory's. Since I have never experienced weld bonding, I'll accept the little knowledge I've gained, and call it good! It's just not that interesting any longer!

Or maybe this one:

http://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/10971158/1

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I seem to recall reading that "secondary seating" was an old trick used by shooters that loaded in large batches. Consequently some of that ammo may sit on the shelf for quite awhile.

I've found some ammo that has been sitting for years on my shelves to be almost impossible to pull bullets using an RCBS collet die puller but when seated just a tad deeper they pulled normally.

Bench rest shooters are commonly seen carrying a tray of primed cases at the range for this reason. Any incidence of weld bond will/can change accuracy as the release on the bullet cannot be uniform or reliable.

Good information on this issue from everyone and it will change how I do things in the future.
I put this issue out there with our locals and the feedback was poor or disbelief.
Recently my safe hunting loads became over pressure and pulling bullets was a chore, so I knew something was up. I kept a few as they were,seated a few a touch deeper and pulled and weighed the rest.I will chronograph these as well...
Tony

Yes this is it and the last one I remember discussing. I searched 'cold weld' and didn't find what I was looking for.

Thanx

Jerry

In Corrosion Control classes they told us similar metals in contact cold weld because, in the case of bullet and case, the copper atoms in the bullet don't know they aren't the same as the copper atoms in the case, so they adhere at an atomic level, sharing electrons. Or so the Chief teaching the class said.
There is also galvanic corrosion, or welding together through electrical micro-voltage process which could be enhanced or encouraged by residual case lubes or cleaning detergents.
But, I don't know for sure. Never studied it in cartridges.
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Now we're cookin' !

......the presence of Zinc (in solution) in the cartridge brass actually leads to / contributes to galvanic transfer, IIRC.

GTC

This is very similar to what Pappy posted last year in the Sticky Bullet Syndrome thread.

"Pappy348 Offline
Campfire Tracker

I did find this on Wiki under "cold welding":

"The reason for this unexpected behavior is that when the atoms in contact are all of the same kind, there is no way for the atoms to “know” that they are in different pieces of copper. When there are other atoms, in the oxides and greases and more complicated thin surface layers of contaminants in between, the atoms “know” when they are not on the same part."

— Richard Feynman, The Feynman Lectures, 12–2 Friction

Thanks, John.
Edited by Pappy348 (02/18/16)"
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These things certainly sound reasonable. I just know from my limited experience with 'cold weld', I know what I used and what I didn't, and I know that powder 'Temp Sensitivity' was NOT the cause.

Plus, after breaking the seal (weld)--the same--loads did not exhibit the xtra pressure signs.

Jerry