Bullet weld

[Brians356]

...
Just curious - not trying to start a pissing contest - I just haven't observed any affect of reloading months in advance of using the reloads but I don't shoot beyond 300 yards. And although I considered myself a precision shooter in that I'm a varmint / predator hunter, I'm not a competitive target shooter.

And do you always seat bullets into clean case necks?

FWIW the only time I was rudely introduced to this phenomenon was with loads sitting for 20 years, and the necks had been scoured clean with a bronze brush.
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[Pwc]

Back in high school, had a science teacher thar had a small sheet of lead with a thin layer of gold "attached" to it at the ends. He said it was a out 60 years old then. The idea was from the old alchemist's idea of turning lead into gold. He was looking to see if the surface atoms/molecules would "exchange". Under a microscope, it was hard to tell where the border was, some spots looked to have combined. 60 years then plus 58 more....wonder what it looks like now.

Any chemistry teachers oit there?

 

[Laurie]

In my opinion, even if the core is steel, if copper plated or copper jacketed, you still end up with only brass alloy and copper in contact with each other. The core material is irrelevant.

I didn't say the core might be steel (which it sometimes is in fact but as you say is irrelevant), rather the jacket which is then given a copper wash mostly to stop it rusting. This was a very common practice in European military ammunition, and is still commonly found in East European / Russian 7.62X39 and 7.62X54mm milspec, some Chinese too. Norma also used this system until the 80s or 90s in the bullets used in its commercial ammunition although with a lead core. Very few people realised the bullets had steel jackets as the copper wash was very good and it appeared to be gilding metal.

When known by users, it often caused worries about excessive barrel wear, but in fact steel jacketed bullets appear to cause no more wear than gilding metal ones.

 

[Jackal2016]

I didn't say the core might be steel (which it sometimes is in fact but as you say is irrelevant), rather the jacket which is then given a copper wash mostly to stop it rusting. This was a very common practice in European military ammunition, and is still commonly found in East European / Russian 7.62X39 and 7.62X54mm milspec, some Chinese too. Norma also used this system until the 80s or 90s in the bullets used in its commercial ammunition although with a lead core. Very few people realised the bullets had steel jackets as the copper wash was very good and it appeared to be gilding metal.

When known by users, it often caused worries about excessive barrel wear, but in fact steel jacketed bullets appear to cause no more wear than gilding metal ones.

I have seen that similar style copper wash on 7.62x51 (or 308) in the past too, steel case and bullet coated. My brother had a bunch of these when he picked up a cheap Norinco (I think) semi auto 308 (or 7.62x54) the cartridges might've been Norinco as well.

 

[Namibian]

Weird phenomena indeed, but very real. Anybody that doubts that it is real needs to run their own experiment with an open mind. Load long, store for at least 3 months, reseat and watch seating force. Or try to pull the bullets with a collet bullet puller.

In my experience, shiny clean necks makes it worse. So tumbling is better than ultrasonic cleaning. The longer you store a box of ammo, the worse it gets. Dry lube, either mica or graphite makes it better. Car wax (small amount) in the tumbler helps too.

[BTW: New bullets are wax coated when it arrived from the factory.]

Reseating the night before, or reseating at the bench is the best cure.

Side note: Moderate (50%) changes in seating pressure at distances below 600 yards have limited impact on bullet speed or point of impact in a hunting rifle that shoots half MOA groups at 100. I tested 50 round with different size bushings, measured seating force with the K&M arbor press with the force measurement tip, wrote the number on the case with a sharpie, and in my notebook. Plotted speed vs. seating force in Excel, and it was a wild scatter plot, with no clear relationship. Will a different point of impact be noticeable at 1000 in a BR rig that shoots in the ones at 100? Probably yes. But i don’t own such a gem right now, so not able to run that experiment.

But if the seating force goes up from 15 pounds to 100 lbs plus, i bet it will have an impact in any rifle. So: Reseat the night before.

 

[rogina]

Weird phenomena indeed, but very real. Anybody that doubts that it is real needs to run their own experiment with an open mind. Load long, store for at least 3 months, reseat and watch seating force. Or try to pull the bullets with a collet bullet puller.

In my experience, shiny clean necks makes it worse. So tumbling is better than ultrasonic cleaning. The longer you store a box of ammo, the worse it gets. Dry lube, either mica or graphite makes it better. Car wax (small amount) in the tumbler helps too.

[BTW: New bullets are wax coated when it arrived from the factory.]

Reseating the night before, or reseating at the bench is the best cure.

Side note: Moderate (50%) changes in seating pressure at distances below 600 yards have limited impact on bullet speed or point of impact in a hunting rifle that shoots half MOA groups at 100. I tested 50 round with different size bushings, measured seating force with the K&M arbor press with the force measurement tip, wrote the number on the case with a sharpie, and in my notebook. Plotted speed vs. seating force in Excel, and it was a wild scatter plot, with no clear relationship. Will a different point of impact be noticeable at 1000 in a BR rig that shoots in the ones at 100? Probably yes. But i don’t own such a gem right now, so not able to run that experiment.

But if the seating force goes up from 15 pounds to 100 lbs plus, i bet it will have an impact in any rifle. So: Reseat the night before.

I noticed that moly coated bullets that were loaded for a year did not crack when seated deeper. Maybe the only benefit.

 

[cw308]

I use the dry lube making seating smooth with the same consistent seating pressure , also read about the cold weld and using the dry lube would help . The thing with cold weld pulling a bullet from the neck and a fired case is a big difference , that fired case is pretty hot so adding that kind of heat would the weld really matter?

 

[K22]

And do you always seat bullets into clean case necks?

FWIW the only time I was rudely introduced to this phenomenon was with loads sitting for 20 years, and the necks had been scoured clean with a bronze brush.
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No - after the first reload on virgin brass the necks contain powder residue - I've never brushed them with a bronze brush. I get about 15 to 17 reloads out of a case depending on the caliber so reloaded rounds, except for the first reload have necks containing powder residue.

Since I do a lot of varmint hunting and range time beginning in the spring I often load up in the winters months since once summer begins I'm busy at the range / hunting / yard / house work so it's convenient for me to have rounds pre-loaded during down times in the winter. Most of those cases have been fired at least once before. I've never experienced any abnormal results, i.e. radical POI changes or group changes with these pre-loaded rounds.

 

[Brians356]

No - after the first reload on virgin brass the necks contain powder residue - I've never brushed them with a bronze brush. I get about 15 to 17 reloads out of a case depending on the caliber so reloaded rounds, except for the first reload have necks containing powder residue.

Since I do a lot of varmint hunting and range time beginning in the spring I often load up in the winters months since once summer begins I'm busy at the range / hunting / yard / house work so it's convenient for me to have rounds pre-loaded during down times in the winter. Most of those cases have been fired at least once before. I've never experienced any abnormal results, i.e. radical POI changes or group changes with these pre-loaded rounds.

My conclusion is that by leaving combustion residue inside the necks you have avoided the effect discussed here.
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[K22]

My conclusion is that by leaving combustion residue inside the necks you have avoided the effect discussed here.
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Yea, I kind of figured that and perhaps that distinction should be made when this issue of bullet weld is discussed.

Yet I still have a question about factory ammunition. While I shoot reloads exclusively I've seen some amazing groups shot with Federal Premium which is loaded with virgin brass, i.e. cooper jacket against "bare brass case" or do they use some special treatment on the bullet or case neck surfaces to prevent "bullet weld?"

 

[Laurie]

While I shoot reloads exclusively I've seen some amazing groups shot with Federal Premium which is loaded with virgin brass, i.e. cooper jacket against "bare brass case" or do they use some special treatment on the bullet or case neck surfaces to prevent "bullet weld?"

I've wondered about that myself. (I'm another fully paid-up member member of the leave-the-carbon-film-inside-case-necks brethren). I believe most brass manufacturers dip newly finished cases in an acid solution of some sort. This may prevent any 'weld' occurring.

Lapua AFAIK doesn't do this and it was with new Lapua cases (and Lapua bullets) that I had the 50% of cartridges in a box produce trouble described somewhere early on in this thread.

 

[Namibian]

I've wondered about that myself. (I'm another fully paid-up member member of the leave-the-carbon-film-inside-case-necks brethren). I believe most brass manufacturers dip newly finished cases in an acid solution of some sort. This may prevent any 'weld' occurring.

Lapua AFAIK doesn't do this and it was with new Lapua cases (and Lapua bullets) that I had the 50% of cartridges in a box produce trouble described somewhere early on in this thread.

Yep, leaving some black carbon residue in the neck helps to avoid “bullet weld”. Ran the experiments and confirmed that.

Some context: Initially used an ultrasonic cleaner and the brass was pristinely clean, zero carbon in the neck. Bullet weld would show up in 1/3 of the loaded rounds within 3 or 4 days. Got very bad after 3 weeks. Seating force would go up from the 20’s to 80 lbs plus.

Then switched to a vibratory tumbler with untreated walnut media and my impression at the time was that it got better, but the problem did not entirely go away. Wait long enough (2 or 3 weeks) and the bullets would reseat with a sudden think. K&M press with the force measurement tip reported 1.5 to 2.5x increase in seating force (lbs), nothing as excessive as before, but NOT the butter smooth seating i had at the time when originally seating the bullets. So better but not a complete cure.

Then somebody on snipers hide suggested Nu-Shine polymer car wax (the type you apply only once a year). That really made a difference.

Today stuck a good quality bore scope (with a lot of ‘amplification’) into my fired brass, and noticed that seating the bullet into the brass leaves very shiny scratch marks on the inside of the neck. Bare brass! Bullets also show mild scratches with the naked eye. Neck tension is moderate, around 0.002”. Maybe i should come down some more...

I think the polymer wax and the carbon in the neck reduces the scratching and consequent exposure of bare metal. Since the bullet will likely be scratched at the same location as the brass, you likely end up with bare copper jacket making hard contact with bare brass (freshly exposed). I would not be surprised if two metals started to interact and corrode due to the presence of water vapor inside and outside the case (humidity). Powder kernels are hygroscopic and absorbs some amount of water vapor if you leave it out in the open for a day. No idea what exact chemistry occurs or why. But something bad happens!

I still use the mix of mineral spirits (which dissolved carbon on the outside of the brass, does almost nothing to the inside of the brass), and Nu-Shine, plus mica dry lubricant applied to the bullet, but now load long and reseat every time before i go to the range. Good / better results in terms of SD and group size.

Run your own experiment and see what you get.

 

[Brians356]

Yep, leaving some black carbon residue in the neck helps to avoid “bullet weld”. Ran the experiments and confirmed that.

Some context: Initially used an ultrasonic cleaner and the brass was pristinely clean, zero carbon in the neck. Bullet weld would show up in 1/3 of the loaded rounds within 3 or 4 days. Got very bad after 3 weeks. Seating force would go up from the 20’s to 80 lbs plus.

Then switched to a vibratory tumbler with untreated walnut media and my impression at the time was that it got better, but the problem did not entirely go away. Wait long enough (2 or 3 weeks) and the bullets would reseat with a sudden think. K&M press with the force measurement tip reported 1.5 to 2.5x increase in seating force (lbs), nothing as excessive as before, but NOT the butter smooth seating i had at the time when originally seating the bullets. So better but not a complete cure.

Then somebody on snipers hide suggested Nu-Shine polymer car wax (the type you apply only once a year). That really made a difference.

Today stuck a good quality bore scope (with a lot of ‘amplification’) into my fired brass, and noticed that seating the bullet into the brass leaves very shiny scratch marks on the inside of the neck. Bare brass! Bullets also show mild scratches with the naked eye. Neck tension is moderate, around 0.002”. Maybe i should come down some more...

I think the polymer wax and the carbon in the neck reduces the scratching and consequent exposure of bare metal. Since the bullet will likely be scratched at the same location as the brass, you likely end up with bare copper jacket making hard contact with bare brass (freshly exposed). I would not be surprised if two metals started to interact and corrode due to the presence of water vapor inside and outside the case (humidity). Powder kernels are hygroscopic and absorbs some amount of water vapor if you leave it out in the open for a day. No idea what exact chemistry occurs or why. But something bad happens!

I still use the mix of mineral spirits (which dissolved carbon on the outside of the brass, does almost nothing to the inside of the brass), and Nu-Shine, plus mica dry lubricant applied to the bullet, but now load long and reseat every time before i go to the range. Good / better results in terms of SD and group size.

Run your own experiment and see what you get.

How and to what do you apply the wax?
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[simo hayha]

I just dump wax in the tumbler

 

[Brians356]

I just dump wax in the tumbler

So you no longer leave the sooty residue inside the neck. Got it.
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