Why lube?

[jag2]

Don't know too much about casting and don't shoot too much lead,
primarily because of the smoke which I presume is a result of the lube.
Exactly what is the purpose of lube? Is it just to help get the bullet
down the barrel? If I don't like the lube that comes on the bullet can it be
removed and relubed with something else? If so, what? I've heard
of moly coating, is that better (less smokey)?

[GP100man]

lube serves 2 purposes :1 to actually lube the bore to enhance accuracy& to prevent guilding metals to contact the bore.
2 to help seal the bore from the pressures forcing the bullet out.

most of the time ya get the most trouble with the second, if bullet does`nt fit tite then gases go by causeing leading & it blows most of the lube out of the groove & burns it , thus the smoke.

yes ya can add liquid alox (even smokier)
yes ya can pan lube after cleaning (boiling) the old lube out .

the molly lubeing is mostly for very soft swaged bullets & does`nt work well on cast.

[armoredman]

I like Lee Liquid Alox, very easy to use. Smoke isn't too bad for me. :) But, I shoot outdoors only, might be an issue in a cramped indoor range with inadequate ventilation.

[totalloser]

I don't think you can moly coat lead at all. IMO the home moly kits are a pita and a waste of time. I will never use mine again. I don't know if moly would work if you could coat lead with it, but I have never heard of it done.

Basically the lube is to prevent lead fouling. Last I heard, no one *really* knows how/why it works since the environment in the barrel is not terribly conducive to study-(temps pressures) but if you remove the lube, you will have terrible lead fouling.

[Unclenick]

The lube is, as TL says, to prevent lead build-up in the bore. There is no gilding metal in cast bullets; that's what jackets are made from. Without jackets, the softer cast and swaged bullets are stripped of their metal rather more easily. So, when pressure bumps the bullet up, giving it a lot of radial pressure, that raises the friction in the bore, cause the metal to rub off. The lube, if it has good film strength, works kind of like a mold release to prevent the bond from forming.

Note that bore friction is not the only source of leading. Gas bypass is the nastiest. It happens any time the lead fails to obturate (seal off) the bore completely, and gas blows past it, blowing metal off with it, and splattering it into the bore. This makes for nasty leading and the gas cut part of the bullet usually favors one side, so the bullets unbalance a little and lose accuracy.

When either type of leading happens, the lead can thicken until it forms a constriction. All lead bullets passing through bore constrictions start getting gas bypass and gas cutting at their base, making the leading and the accuracy still worse.

If a bore is rough or the steel itself has a constriction, as is not uncommon in revolver barrels where they screw into the frame, or in barrels with dovetails cut into them for sights, lubricant alone will not stop leading, and you will need to lap or to firelap these guns before lead bullets will shoot well in them.

[IllinoisCoyoteHunter]

Why lube?

Have you ever tried to stick something really hard and oversized (bullet) in a really tight spot (bore)? ;)