rub off spin off

[gandydancer]

with a cast and lubed bullet on going out the bbl of a firearm is the lube rubbing off on the barrel or is it spinning off? or both? GD

[Jim]

People been tryin' to answer that question for decades.

[zomby woof]

http://www.lasc.us/Fryxell_Book_Chapter_5_Lubrication.htm

[x101airborne]

I relate it to the question "What came first... Chicken or the egg?"

Maybe spin has to do with holding it against the barrel so it liquifies from friction, then discharges with gasses as the boolit leaves the barrel. I would THINK that centrifugal forces amount to something due to the "lube star" on the front of the muzzle. I never really gave it much thought before and this is just a quick guess.

[geargnasher]

If good obturation is achieved, and IMO lube has a part in perfecting the bore-barrel seal, then the lube stays in the grooves mostly, but small gas leaks pressurize the grooves. When the grooves clear the muzzle crown, they instantly depressurize to atmospheric pressure from whatever peak pressure was. Sometimes this causes the lube to depart the boolit at that point, but sometimes not. If the boolit loses much lube while going down the barrel, it's because it's getting blown out ahead of the boolit due to obturation failure, and it's likely to lead some too due to gas-cutting. Normally, only the faintest film of lube is left behind in the barrel after each shot, and if the lube viscocity is high enough for the pressure, that lube film will remain constant and not accumulate (purge flyers will occur if it does), so the amount lost to coating the bore after the first, fouling shot is virtually none.

Gear

[runfiverun]

like gear i think of the lube much like a piston ring only in semi to liquid form.
once it leaves the Bbl it may be flung from the boolit [hopefully all at once]
or not [and hopefully none of it]
the in the bbl part he already covered..

[stubshaft]

You forgot option #3 - stays on boolit.

[Sonnypie]

Ya know, the darn things are going so fast, I've never been able to tell.
Not even with my BLOOP loads.
Of course, maybe I blinked....

[DLCTEX]

I think there is also some hydraulic pressure created by the collapse of the boolit, as it's kicked down the barrel, that forces lube against the barrel.

[dragonrider]

I think there is also some hydraulic pressure created by the collapse of the boolit, as it's kicked down the barrel, that forces lube against the barrel.

I believe that is exactly right.

[geargnasher]

As the barrel lands slice through the driving bands they're going to displace some lube, so I'd have to agree also.

Gear

[gandydancer]

Good info. thanks you all. GD

[Mk42gunner]

In my experience, hard crayon lubes on purchased bullets tend to stay with the bullet. I have recovered bullets that still had all the lube on them.

Soft lubes like FWFL or SPG are the ones that come off in flight. I think it is being spun off by centrifugal or centripetal force ( I never can remember which it is).

Robert