Originally Posted by ironbender
Originally Posted by Jordan Smith
Originally Posted by Mule Deer
Apparently!

Actually, I dunno how the stuff works. Doug Burche told me it filled in imperfections in the bore, but since it also apparently works on super-smooth bores.

Maybe it's like a Thermos bottle, which keeps cold stuff cold and hot stuff hot. :-)


DBC fills in the pores of the steel and has a lower coefficient of friction than steel, so once cured it "scrapes" less material off the bullet jacket, and as you know, it relinquishes it much easier than steel does, as well.

Taking this to the next logical step (uh-oh smile ) is there a consequent drop in pressure/speed after application which allows a higher charge to attain the same pressure/speed?

Or is that just crazy talk?


Velocity of the bullet comes from sustained pressure as the bullet is pushed down the bore (bear with me). There are two primary sources of this pressure that is generated- the inertia of the bullet and the tight fit between the bore and bullet, providing resistance against the rapidly expanding, hot gases in the chamber, as well as the coefficient of friction between the bullet and the bore. The bullet's inertia and bullet/bore fit is by far the biggest contributor to resistance, and therefore pressure generation, with coeff. of friction between the bullet and bore being a very minor portion. An analogy would be you trying to push a 10,000 lbs boulder through a doorway in your living room (don't ask me how it got there) on carpet versus linoleum. The difference in resistance the boulder gives you when pushed on carpet versus linoleum is pretty insignificant, considering the amount of force required to overcome the inertia of the boulder and squeeze it through the doorway. This can be seen when we modify the friction between the bullet and the bore by either changing the bullet material or the bore surface. In this case, the coating fills in pores and reduces friction, but the change in overall pressure is minimal.

But the reduction in the coefficient of friction is enough to prevent the bullet's jacket from scraping off and being deposited in the pores and crevices of the bore.

Here's a couple of 1000 words to show you what I mean:

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