Bullet lube... I don't understand.

Stupid question perhaps but I'll ask... 

On a cast bullet with lube grooves, (not the micro groove Lee mold type) what does the lube do? I tumble lube my own cast bullets and it gets into grooves as well as the surface that actually contacts the bore... and I thought lube was to help reduce leading by slicking up the contact between the bullet and bore... so if its in a groove then how does it contact the bore or support the bullet against the bore. When the powder charge ignites and such forces are created (pressure, gases, etc.) does it cause a flash melt of the bullet lube? I have recovered commercial bullets from my pistol berm with lube still intact in the groove before so I wonder - whats it good for?

This will answer your question.
http://www.lasc.us/fryxelllubecastbullets.htm

Last paragraph in link.

    In summary, bullet lube is pumped from the lube groove to the barrel surface by compression, linear acceleration and radial acceleration. In addition, lube is injected forward during the firing process, as the result of high-pressure gas leakage into the lube groove. This injection process forms a floating fluid gasket around the bullet, and serves to limit gas cutting and is a kind of ballistic stop-leak. Hard lubes must first melt before they can be pumped or injected by any of these mechanisms. By incorporating moly into the mix, the lube delivered to the barrel surface can serve to prevent adhesion of future leading deposits by passivating the steel surface.


If you have ever watched a slow motion video of a pistol being fired you see gasses exiting before the bullet, it makes the above completely clear.  
- Dave

Tumble lube does seem more effective. It can be a cure for conventially lubed bullets that lead. As Tim said, if the recovered bullet still has the lube intact in the groove, it wasn't very effective.

desben wrote:Tumble lube does seem more effective. It can be a cure for conventially lubed bullets that lead. As Tim said, if the recovered bullet still has the lube intact in the groove, it wasn't very effective.

If you have conventially lubed bullets that lead, the LAST thing I would look at would be the lube.

Don

dronning wrote:This will answer your question.
http://www.lasc.us/fryxelllubecastbullets.htm

Last paragraph in link.

    In summary, bullet lube is pumped from the lube groove to the barrel surface by compression, linear acceleration and radial acceleration. In addition, lube is injected forward during the firing process, as the result of high-pressure gas leakage into the lube groove. This injection process forms a floating fluid gasket around the bullet, and serves to limit gas cutting and is a kind of ballistic stop-leak. Hard lubes must first melt before they can be pumped or injected by any of these mechanisms. By incorporating moly into the mix, the lube delivered to the barrel surface can serve to prevent adhesion of future leading deposits by passivating the steel surface.


If you have ever watched a slow motion video of a pistol being fired you see gasses exiting before the bullet, it makes the above completely clear.  
- Dave

Thank you very much, I enjoyed reading that article. It was very interesting to me especially because its explaining things I have not had explained before. When I cast, load and shoot, I just make sure the bullets are the right size, lube em and load and shoot. I never gave a thought as to whats going on with the lube until recently when, like I said earlier, I found bullet lube still intact on a spent slug and wondered .... whats going on there? Now I have some insight. Thank you dronning.

USSR wrote:

If you have conventially lubed bullets that lead, the LAST thing I would look at would be the lube.

I don't disagree. Bullet hardness may be wrong for the velocity, or they may be sized innapropriately for the firearm, for example. However, when you have a batch of conventially-lubed bullets that lead, giving them a coating of alox will often resolve the problem. I guess you could say it's a "band-aid" fix.

USSR wrote:If you have conventionally lubed bullets that lead, the LAST thing I would look at would be the lube.

Don

I'd say that is mostly correct, but not all lubes are created equal.  Tumble lubing may solve minor leading issues.

- Dave

So am I wasting time and money using 45/45/10 on my bullets that have lube in the groove?  Don

Magload wrote:So am I wasting time and money using 45/45/10 on my bullets that have lube in the groove?  Don

First thing I would look at is diameter in relation to your barrel's groove diameter.   A lead bullet should be larger than groove diameter.   How large doesn't seem to matter, as long as the loaded cartridge chambers properly.   I've loaded .358" bullets in 9mm Luger cases and they shot fine.   Next thing I would look into is the BHN of the bullets.   Commercial lead bullet manufacturers have done a great job of convincing guys that "the harder the better".   Seems like most of the commercial manufacturers offer either 12 or 18 BHN bullets.   Think about it, Elmer Keith cast bullets for his 44 Magnum with a hardness of about 11 BHN.   At the velocity/pressure levels we are talking about with the .45 ACP, there is simply no need for these excessively hard bullets.   Lastly, I would look at the lube.   These same commercial lead manufacturers that give you too hard bullets, also lube them with a lube the consistency of crayons.   Hey, hard lead and hard lube hold up well in shipping, and they sure do look pretty.   To answer your question, do what you have to do to use up those bullets, then look around for something better.   Okay, rant off.

Don

Magload wrote:So am I wasting time and money using 45/45/10 on my bullets that have lube in the groove?  Don

If the bullets didn't lead the barrel no need to use it.
I tumble 45/45/10 right over the existing lube on a couple of bullets that lead a little bit, it eliminates the leading completely.

There are a few folks that remove the existing lube and misc. lead flakes on their bullets by tumbling in solvent, then they tumble lube with 45/45/10.  Jerry Keefer did this on his Remington 148gr HBWC, I'm not sure if he did it on other cast bullets.

- Dave

I am only shooting Dardus in the 38 Super and Zero in everything else.  I have had no leading but don't want any and if 45/45/10 might help I sure am willing to use it.  Don

I have a lot of the old NRA formula lube I want to sell, hollow as well as solid sticks.Tamarack 2138F/beeswax, $2.50 a stick plus freight. Best lube I used.Send  PM if interested.
Tom Ginovsky

Jerry washed and relubed 38 and 45. My memory is that the 45-45-10 allowed him to use softer Star bullets that otherwise leaded. But he also believed that removing the small lead flakes lead to better results. The anecdotal evidence from several people support this theory.

I have some dewc 38s that are .358 that you can scratch with a finger nail but have a hard blue lube. What solvent would you use to remove, gasoline be good? Also would putting them in a coffee can and swishing around for a bit work.
Stan

Gasoline or naptha, Coleman gas.

Thanks Jim, I'll use the cheap stuff and swirl that around, it probably works the best.

For large amounts of bullets, a solvent is probably the best way to remove the lube. For smaller quantities (say a few dozen), you can use boilling water in most cases. Just put the bullets in a strainer and pour boilling water over them. It melts the lube away.