Bullet weld

[Wedgy]

It not only does both of those, cold bore shots are always in the group. Really not a big deal in matches, but it is in long range hunting. It does have some downsides, mostly in the coating process, but performance is flawless. Maybe we should start a new thread

I agree with all of these points ! I am a believer in HBN but I don't think it needs another thread as there are plenty ~15 page+ ones here and on LRO. There is plenty of info to read;
http://www.longrangeonly.com/forum/showthread.php?1796-hBN-bore-treatment&highlight=BULLET+coating

 

[jbs2014]

but some guys are claiming that cold weld caused case head separations or neck splits , and even detonation which damaged the gun in some cases----some factory ammo sits there for 15-20 years before it gets shot (OR EVEN LONGER), just trying to figure out why it doesn't seem to be a big issue with factory ammo

I am curious about that as well. I have a large supply of .50 BMG ammo that is several years old. Some milspec and some from Thunder Ammo and other smaller manufacturers and I have not had any of those issues either. I did have case head separation once but that was with a batch that I found was loaded way to hot and with poor quality brass.

 

[jbs2014]

Could also have some residual moisture in the case if you wet tumble, I live in the desert(SoCal) so we don't have a lot of moisture here so I suppose that helps.
I gave up on aggressive brass cleaning(wet tumbling/ultrasonic) as I felt it was too clean, too much gripping on the neck when seating bullets. HBN tumbled bullets and Q-tip with Imperial was on the case mouth seems to work for me. I also write the date they were loaded.

I still do the ultrasonic cleaning but I tumble the brass in the dry media tumbler. Think the residual polish left over in the necks from the dry tumbling could also possibly help prevent the case welding?

 

[Orange Dust]

I agree with all of these points ! I am a believer in HBN but I don't think it needs another thread as there are plenty ~15 page+ ones here and on LRO. There is plenty of info to read;
http://www.longrangeonly.com/forum/showthread.php?1796-hBN-bore-treatment&highlight=BULLET+coating

I know, just didnt want to hijack. Knowing what i know now, after using the stuff over 10 years, i would just as soon hunt with a round nose bullet as an uncoated one in my long range rifles. Yes, the stuff is a lot of trouble. That's because it is worth it.

 

[Bigeclipse]

I'd love to be able to load extra ammo that I could safely store and count on for a year or two. I've tried leaving the carbon in the neck of the case, this did not help at all.
When I pull bullets there is a little white residue left inside the case neck that looks like battery corrosion. I suspect electrolysis is the culprit. I would think that a non conductive coating of some sort would help.
The problem with this is that it takes a long time to find out if a potential solution actually works.
Crimping is a solution that I don't want to get involved in. I believe this is why virtually all factory ammo is crimped.

I don't think I've seen any factory rifle ammo that is crimped but maybe it is a subtle crumb?

 

[Echo Charlie]

To avoid the so called "cold weld" between bullet and case, anybody tried applying a bullet lubricant like liquid alox from Lee, commonly used on cast lead bullets?
Roll the bullets over a small amount of alox.
Allow to dry and seat them.
Remove the excess from the bullet and neck.
Will try it soon

 

[Orange Dust]

To avoid the so called "cold weld" between bullet and case, anybody tried applying a bullet lubricant like liquid alox from Lee, commonly used on cast lead bullets?
Roll the bullets over a small amount of alox.
Allow to dry and seat them.
Remove the excess from the bullet and neck.
Will try it soon

Just coat the bullets with HBN and be done with it.

 

[Bob Wright]

So, the curiosity was eating at me. I loaded some hunting ammo in October 2018. I shot it at 600 for a drop test at distance. It was vertically spread out 7".
I ran another test today to see what changes it would make by:
-Shooting 5 with nothing done,
-5 with bullets pulled out completely, check weight of charges, neck size, re- seat,
- 5 more with bullets pulled up .050 and re-seated with no neck size.
I didn't notice any "sticky" condition so "bullet weld" is not at play.
The velocity avg and SD did change, ES is high at ~20FPS avg.
The group shapes and location moves vertically, with flyers.
This load was never developed for tuning at this range. I was doing my usual development at 200 and they all are repeatable and all touching.
I believe my vertical stringing is more of a missed accuracy node and neck sizing "only" issue.
Lesson learned: need to always test at distances I intend to shoot, record on paper targets and tweak.
I'll try the ladder test again with full length sizing first, and see where an accuracy node might really be. Start from there and just keep trying one variable at a time.
7mm RM
175 LRAB
Fed 215 primers
RE23 powder
Nosler brass, annealed, neck sized, neck turned for .004 diametral clearance, fire formed.
26" Krieger 8.5 twist heavy sporter.

 

[jbs2014]

I recently pulled some .408 bullets with the CH4D bullet puller. I almost snapped the arm off of the press and the projectile barely moved on four of the rounds. I don't even want to think about what would have happened had they been fired. The ammo was about 10 years old or so. I find it odd because I have fired .50 BMG ammo that was much older without any issues.

 

[Frog4aday]

This is about the third thread (at least) talking about "bullet weld" and I can't recall that it has ever been conclusively pinned down why some people experience bullet weld and some do not. And it would be really nice to know how to absolutely avoid it.

One thread postulated that people that were cleaning brass via the wet method (and steel pins) and that was cleaning the cases 'too clean' (no carbon residue on the necks) which allowed the metal of the brass and the copper of the bullet to be in direct contact leading to a form of galvanic corrosion, causing the 'bullet weld' issue. But that was just a theory as far as I could tell.

Others say they lube the necks when seating bullets, hoping the 'lube' will prevent the bullet welding, but again, there is no proof that worked or didn't work. And do we go with dry lube (graphite) or a paste type lube...or does it even matter?

Does someone have a link to a URL where this bullet weld issue has been researched and a definitive cause and cure has been posted? I'd love to see it.

 

[Bob Wright]

This is about the third thread (at least) talking about "bullet weld" and I can't recall that it has ever been conclusively pinned down why some people experience bullet weld and some do not. And it would be really nice to know how to absolutely avoid it.

One thread postulated that people that were cleaning brass via the wet method (and steel pins) and that was cleaning the cases 'too clean' (no carbon residue on the necks) which allowed the metal of the brass and the copper of the bullet to be in direct contact leading to a form of galvanic corrosion, causing the 'bullet weld' issue. But that was just a theory as far as I could tell.

Others say they lube the necks when seating bullets, hoping the 'lube' will prevent the bullet welding, but again, there is no proof that worked or didn't work. And do we go with dry lube (graphite) or a paste type lube...or does it even matter?

Does someone have a link to a URL where this bullet weld issue has been researched and a definitive cause and cure has been posted? I'd love to see it.

So, not being a chemist or metallurgist I did stay at a Holiday Inn once, lol.
I looked up "metallic bonding", which is a pretty dry read. It's at a molecular level.
Alex Wheeler, highly respected, as noted in other threads at LRH, had covered the topic of cleaning necks with a nylon brush only, leaving whatever the black deposits in the necks are, but not to remove it. This "carbon" (we call it) is extremely hard, like diamond hard, definitely provides a barrier, and a slicker surface than bare brass with no oxide because we (me) tried so hard to remove it. I am running some tests to correct loading issues I have, one of which is to not remove the carbon. See my post #36 target. My groups changed vertically and shape by simply moving the bullet and re-seating in the case, all else being identical.
I'm pretty sure I'm on the edge/out of an accuracy node, and that may be the major problem here.
I didn't detect a weld, any "pop" of the press re-seating bullets. It's like I just loaded them on day one. Question is, what effect did moving the bullet on squeaky clean brass, over a year later? Alex was clear though. Leave the carbon, nylon brush the necks only. I'll try it.
Note, I had no direct info or link to bullets and cartridge "welding", just bonding, galling, smearing of materials and what the science is behind it and how to prevent or reduce it. Oxides and carbon were a "+" in prevention.
Testing our stuff and reporting back is helpful.