Hi-Tek Powdered Coating

From looking at pictures like the one from mtngun in post #40 where the base of the bullet shows that molten (liquefied) lead appears on the base of the plain base bullet.  I believe that the base was liquefied or heated to a molten point and the then liquid lead was pushed up onto the sides of the bullet after it left the barrel. 452.1 said: I might add that it is a LOT harder on the bullet, that is very hard and basically has little protection, to start it from a dead start touching or engraved into the rifling than it is to have it moving some BEFORE it starts into the rifling. Designed and fitted correctly, the bullet does not suffer from doing this........"

Any time you load with the bullet forced into or touching  the lands you are going to raise pressure.  According to Charles Law ( I think it is this one) there is a direct relationship between pressure and temperature.  The higher the pressure the higher the Temp.  When I was diving we used to call Charles Law the “Hot Tank Law".  If you filled the vessel to capacity (rated PSI) quickly without bleeding the heat off ie. filling the tank while it was in a water bath.  The tank would be almost too hot to touch.  When it cooled down the pressure in the bottle was usually a couple to 300 PSI less.  There is also a direct relationship between pressure and velocity.  The higher the pressure the higher the velocity until you reach the point where you are digging pieces of brass, wood splinters, and steel out of your hide because the gun let go and now looks like something that Elmer Fudd tried to shoot Buggs with.

Taking the above into account we can now get an idea of how great the pressure differential is between the same cartridge with the bullet seated into the lands and one with a degree of jump or freebore before it hits the rifling.  Chronographing the two rounds one with the bullet seated some distance from the rifling, and the other with the bullet seated into the rifling will give us an idea of the pressure difference  between the two types of loads especially if we can get a couple of pressure readings at varying velocities.  I'm trying to come up with a way to get a handle on this without spending a couple of three grand on piezeo electric equipment.  If this can be done then you can predict with some degree of accuracy just how fast and how much pressure a given cast bullet can stand before it degrades physically enough to destroy accuracy.

Maybe I should have done this for that Physics 101 paper way back when insead of recoil.  Oh well!! Brodie PS. Thank You for the complement 45 2.1 I really appreciate it.

B.E.Brickey