You s q u e e e z z e the trigger. It slips the sear and the hammer is driven forward by the cocked spring, which drives the flint past the frizzzen generating a shower of sparks to land in the pan holding a tiny charge of fine-grained primer-powder. The powder is ignited and flashes BACK into the barrel of the rifle, where it ignites the main charge, lightly compressed under the lead ball.
When the main charge ignites, it BURNS... it does not EXPLODE (although it happens so fast our PERCEPTION is that an explosion has taken place). When the powder burns, it raises the PRESSURE under the lead ball to tens of THOUSANDS of pounds per square inch. Not for very long, of course... too much pressure for too long will cause the mild steel barrel to fracture. But when the lead ball can MOVE, that is what happens.
Pushed by the pressure of the burning charge, the lead ball is driven from the barrel of the rifle. But since there are several groves in the barrel, the lead ball will follow the groves, which form a spiral, making one complete revolution for every three or four feet of the barrel's length.
Pushed by the pressure of the burning charge, the lead ball is driven from the barrel at velocities as high as two thousand feet per SECOND, although that is a bit higher than the norm. By actual measurement, a comepletely home-made rifle -- lock, stock & barrel -- drove a 0.454" lead ball at a muzzle velocity of 1375 (avg) feet per second.... and since the ball was rotating at the rate of ONE REVOLUTION for every forty-eight inches of travel, it means the ball was rotating at 1375 / 4 or about 345 revolutions PER SECOND... which is about 20,000 rpm. And at 20,000 rpm the spinning ball proves to be remarkably STABLE.
In effect, the lead ball has become a gyroscope that tends to remain stable, which is why the bullet flies true... we hope.
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Can YOU do that? Can YOU build a rifle that will keep your family fed and protect you from those who might try to harm you? The record shows that you can. In fact, the tooling needed to fabricate such a weapon is available to virtually EVERYONE because it is based on easily understood principles. You can even manufacture your own GUNPOWDER... which is why the contraversy over 'gun control' is such a joke.
-R. S. Hoover