Cold solder?

[Kinsman]

In a current post on ammo storage, the subject arose of cold soldering of the bullet to case neck .
This has been discussed on other posts.

Is there any cold, hard evidence that this actually does occur, or is this mostly conjecture?

 

[Greg Langelius *]

Re: Cold solder?

I think it is and it isn't.

Neck tension in handloads has been demonstrated to increase over time. I think this is in part due to springback, and in part due to a form of chemical/ionic reaction that occurs over time when two dissimilar metals are forced into contact under tension.

I think it's real. I wish I could find more definitive supporting evidence. I looked.

Greg

 

[High Binder]

Re: Cold solder?

It's a dipole effect but without really looking at the specifics of the brass/copper interaction I can tell you that it's not going to be a real issue in a human's life span... It's a lot more of an issue when dealing with 2+ vastly different metals, copper & brass are to similar (copper gives brass its gold color).

I could look into it in depth and do the math but there really is no point.

 

[High Binder]

Re: Cold solder?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body"> I think this is in part due to springback</div></div>

I would venture that it's actually a normalizing effect as spring-back should occur instantly. Time is the factor in normalizing.

Thoughts?

 

[bohem]

Re: Cold solder?

Brass not only work hardens, it also age hardens. The increased neck tension with time is due to the brass aging.

I don't have any more input on the cold soldering, while it's possible I suppose I haven't seen any hard evidence to prove one way or the other.

As of now, I've chalked cold soldering up there with builers not wanting to build a mag cartridge rifle out of 416R for extreme cold weather.

 

[sinister]

Re: Cold solder?

It is one of the reasons some military ammunition is eventually retired and surplused. Certain types are not affected due to the use of a chemical neck sealer between jackets and case neck.

Army documented a LONG time ago and it was discussed in Precision Shooting. There was also some conjecture that moly-coating helped ameliorate cold soldering somewhat with an unlike barrier between jacket and case neck.

 

[bohem]

Re: Cold solder?

sinister- Do you have a reference to the PS article? I'm an avid reader for a few years now, I might have missed it or it's not in the collection I've kept since the start of my subscription.

I'll order a back copy if possible.

 

[Fuzzball]

Re: Cold solder?


Clean bullets WILL chemically bond to clean necks over time, how and why I don't know and don't care, but it isn't "soldering".

I once had trouble breaking down loads I'd made many years before for a rifle I no longer had. I finally tried seating the bullets a few thousants deeper to break any adhesion and clearly heard a distinct 'SNAP' when each one broke free. Afterwards, they pulled quite easily.

 

[former naval person]

Re: Cold solder?

Just as Shot in the Dark mentions about dissimilar metals..."Cold soldering" really did occur many years ago in the infancy of jacketed bullets...the Army tried plating bullets with Nickel (I think...read "Hatcher's Note Book" for the details) which resulted in instances of skyrocketing pressures. That was about the time accuracy nuts tried greasing bullets to reduce the pressures...not knowing the source of the problem. They got sloppy, got grease in the chamber, and blew up some rifles.

 

[Grump]

Re: Cold solder?

Get to know your metals science.

And your shooting tech history.

It was a problem with tin-plated jackets during or shortly after WWI, IIRC. No, I wasn't around then.

AFIK, USGI ammo has a tar-like sealant in the case mouth that would more than likely prevent cold soldering. Could be wrong, I don't know what the ammo had back then.

But I can tell you from personal experience that NONE of my Dad's 50-year old reloads have ever demonstrated any signs of jackets bonding themselves to case necks.

True cold soldering is all about electron exchange.

 

[bigwheeler]

Re: Cold solder?

I have pulled down some 30-30 and some 168 Grain Salt Lake City 30-06
military match that had very high pressure signs. The bullets/necks had corrosion
that stuck them pretty tight. About 1/2 of the 30-30 cases were no good. The
06 I reseated and went out and shot.

 

[Kinsman]

Re: Cold solder?

thanks for your replies.
I think that if the problem exists, it is not something that I need to worry about in my lifetime.

David

 

[MarinePMI]

Re: Cold solder?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grump</div><div class="ubbcode-body">
AFIK, USGI ammo has a tar-like sealant in the case mouth that would more than likely prevent cold soldering. Could be wrong, I don't know what the ammo had back then.

</div></div>

Grump,

IIRC it was primer sealant that was used to (quite literally) glue the bullets into the case years ago. The result was an incredibly consistent neck pull, which was one of things they measured to ensure ammunition functioned properly in belt fed machine guns. This info was from a gentleman still currently in the ammunition manufacturing field and has many, many decades in the business.

Some ammo, to this day, is still manufactured this way, though not for the US military if I understand it correctly...

 

[former naval person]

Re: Cold solder?

Sorry that Grump had to correct me on my metallurgy. I think I referred to the Army experience, but my age is telling. Tin it was. And tinning is a basic part of soldering when you are dealing with copper and brass. Reply to MarinePMI...The sealant on both the primers and the necks were for waterproofing...not for consistency. I fired some '54 AP rounds recently. The original gave a 5" group at a hundred. Breaking the seal by seating deeper .01 gave a 1.5 inch group. The originals were issued to me for matches back in the early '60s. They were the most accurate government loads at the time. I only had a few left. End of an era. The last 7.62 rounds I have from the early 70's are sealed. I don't know about the latest .223. JMHO

 

[MarinePMI]

Re: Cold solder?

fnp,

That may very well be the case, though as conveyed to me, the primer sealant was not applied to the entire base of the bullet. As I understand it, the sealant was applied in two long strips along each side of the bullet. I'm not sure of the bullet was seated in a twisted motion to coat the inside of the case neck, or if the two strips prevent the bullet from moving, thereby water proofing the ammunition that way. Not sure...

With the military requirements of ammunition to survive 72hrs of submersion and still function, I could see there being a need for water proofing. That being said, as it was told to me, it was also for consistent neck pull.

Tomato, tomatoe...either way, it was done (for whatever reason) and appeared to have a purpose that did increase neck tension/bullet pull as well as water proofing...

 

[Grump]

Re: Cold solder?

I've seen the tar stuff inside the case necks (ball and Match ammo alike), and it ain't anything like the lacquer-type primer sealant.

 

[Grump]

Re: Cold solder?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bigwheeler</div><div class="ubbcode-body"> I have pulled down [snip] some 168 Grain Salt Lake City 30-06
military match [snip] </div></div>
Salt Lake City ammo was headstamped SL and was only during WWII according to my sources. Was yours black-tip AP? That would be the only .30-06 ever loaded with a bullet of around 168 grains. All .30 Caliber match ammo of any sort was phased out long before M852 was created, using the 168 SMK.

 

[bfoosh006]

Re: Cold solder?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fuzzball</div><div class="ubbcode-body">
Clean bullets WILL chemically bond to clean necks over time, how and why I don't know and don't care, but it isn't "soldering".

I once had trouble breaking down loads I'd made many years before for a rifle I no longer had. I finally tried seating the bullets a few thousants deeper to break any adhesion and clearly heard a distinct 'SNAP' when each one broke free. Afterwards, they pulled quite easily. </div></div>


I can also attest to this, after loading some 44 mag. rounds ( Hornady 300gr XTPs into virgin Rem. cases) I tried to pull apart the sample/dummy round with a Kinetic Puller and no friggin' way was that happenin'...the XTPs hollowpoint actually started to started to open and the lead core started to "flow" out, yet the the jacket and case would not let go of the cold weld it had achieved. I've left that round sitting up on the bench to remind me that "I don't know everything..".

Read this... http://en.wikipedia.org/wiki/Cold_welding ...and this one is better... http://www.keytometals.com/Article51.htm

 

[bigwheeler]

Re: Cold solder?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grump</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bigwheeler</div><div class="ubbcode-body"> I have pulled down [snip] some 168 Grain Salt Lake City 30-06
military match [snip] </div></div>
Salt Lake City ammo was headstamped SL and was only during WWII according to my sources. Was yours black-tip AP? That would be the only .30-06 ever loaded with a bullet of around 168 grains. All .30 Caliber match ammo of any sort was phased out long before M852 was created, using the 168 SMK. </div></div>

It was 1965 white boxed IIRC. It didn't have any of the black sealer in the necks.
It was not AP for sure. Boxes were clearly marked match. That's about all I can
remember other than when I shot the first round I thought it had to have split
the stock. I pulled and weighed powder charges and reseated and they were
fine.

 

[j-huskey]

Re: Cold solder?

Correct name: Cold Welding, a chemical bonding. There is the evidence that Sinister mentions.

This can happen with reloads MORE than with factory ammo, because of the residue in a fired case that is not properly cleaned before loading. I have seen cases that had the neck of the case come off on the bullet. There have been big bangs when this happened and the neck tried to go down barrel with the bullet.
The data I do not have, but some of Sinisters OLD buddies may know where it is.

Dave, you still speak with W.O. Harden?