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i'm not sure you guys are understanding the context of his question. i think what he's wanting is some basic theory of how a bullet is shot through the barrel. it's not a matter of reloading manuals.
the reaction of the gun powder is more of a gradual push than an instantaneous hit when the primer is hit. well, it's 'gradual' if one were comparing flame propogation to the speed of light.
when the primer flashes, the flame front moves to the gun powder, causing it to oxidize very rapidly. this reaction is also exothermic (it gives off heat). i've read that for each mole of gunpowder, it's converted into something like 200 moles of gas, which creates the pressure rise pushing the bullet (someone with more off-top-of-head knowledge should correct if my number is wrong).
anyway, it's really inertia of the bullet that regulates the maximum pressure (which is related to weight, or mass more precisely - pushing a bullet on the moon should take the same amount of energy as pushing a bullet on earth (horizontally, really. the force of acceleration due to gravity applies more to the external ballistics). as the gun powder oxidizes, the bullet meets resistance of the rifling as well, and this along with the inertia of the bullet 'backs-up' the oxidation of the powder. the powder burn is instant if compared to the reaction of the bullet (an object at rest wants to stay at rest...)
now, the maximum pressure of a gun powder load depends on a meriad of variables. one is mass. adding mass to the bullet increases its inertia (the force due to resistance of the rifling should be consistant with the same barrel), thus increasing the 'back-up' of the power burn. this increases the maximum pressure, and can lead to devestating effects (which is why the reloaders on this site strongly urge against it, and rightly so).
another is burn speed. if a powder oxidizes faster, it will reach maximum pressure quicker, and since there is a smaller volume behind the bullet to contain the burn, it can also lead to dangerous side effects. a higher mass bullet on top of a fast powder would be even more disastorous. with slower burning powders, such as the .45 acp, the pressure is built up gradually, ideally taking the entire barrel length to build up maximum pressure.
it's a balance between burn speed and maximum pressure. the ideal load would use a powder that will a: have all of it's powder oxidized, and thus turned into gas, and b: reach maximum pressure just as the bullet leaves the muzzle. this makes sure that all the available powder has converted to gas to add pressure, and that the bullet doesn't slow down due to rifling/etc. drag after the gas reaches maximum pressure.
so, if you add bullet mass, the same powder load for a lighter bullet will result in a higher maximum pressure and thus is ill-advised. backing down the powder charge keeps the pressure at or below saami pressures. this also results in a slower muzzle velocity, since the energy transfer must be constant. because the pressures are the same, the two powder weights *should* apply the same amount of kinetic energy to both bullets, so m*v^2 of one bullet should be equal to m*v^2 of the other bullet. if you increase m of one side, v of the other side (or the square of v) should decrease the same amount.
now, this is by no means the end-all, be-all of internal ballistics. i'm just summarizing some of what i have picked up along the way. if somebody with more experience in the physics/chemistry, please chime in.
the reaction of the gun powder is more of a gradual push than an instantaneous hit when the primer is hit. well, it's 'gradual' if one were comparing flame propogation to the speed of light.
when the primer flashes, the flame front moves to the gun powder, causing it to oxidize very rapidly. this reaction is also exothermic (it gives off heat). i've read that for each mole of gunpowder, it's converted into something like 200 moles of gas, which creates the pressure rise pushing the bullet (someone with more off-top-of-head knowledge should correct if my number is wrong).
anyway, it's really inertia of the bullet that regulates the maximum pressure (which is related to weight, or mass more precisely - pushing a bullet on the moon should take the same amount of energy as pushing a bullet on earth (horizontally, really. the force of acceleration due to gravity applies more to the external ballistics). as the gun powder oxidizes, the bullet meets resistance of the rifling as well, and this along with the inertia of the bullet 'backs-up' the oxidation of the powder. the powder burn is instant if compared to the reaction of the bullet (an object at rest wants to stay at rest...)
now, the maximum pressure of a gun powder load depends on a meriad of variables. one is mass. adding mass to the bullet increases its inertia (the force due to resistance of the rifling should be consistant with the same barrel), thus increasing the 'back-up' of the power burn. this increases the maximum pressure, and can lead to devestating effects (which is why the reloaders on this site strongly urge against it, and rightly so).
another is burn speed. if a powder oxidizes faster, it will reach maximum pressure quicker, and since there is a smaller volume behind the bullet to contain the burn, it can also lead to dangerous side effects. a higher mass bullet on top of a fast powder would be even more disastorous. with slower burning powders, such as the .45 acp, the pressure is built up gradually, ideally taking the entire barrel length to build up maximum pressure.
it's a balance between burn speed and maximum pressure. the ideal load would use a powder that will a: have all of it's powder oxidized, and thus turned into gas, and b: reach maximum pressure just as the bullet leaves the muzzle. this makes sure that all the available powder has converted to gas to add pressure, and that the bullet doesn't slow down due to rifling/etc. drag after the gas reaches maximum pressure.
so, if you add bullet mass, the same powder load for a lighter bullet will result in a higher maximum pressure and thus is ill-advised. backing down the powder charge keeps the pressure at or below saami pressures. this also results in a slower muzzle velocity, since the energy transfer must be constant. because the pressures are the same, the two powder weights *should* apply the same amount of kinetic energy to both bullets, so m*v^2 of one bullet should be equal to m*v^2 of the other bullet. if you increase m of one side, v of the other side (or the square of v) should decrease the same amount.
now, this is by no means the end-all, be-all of internal ballistics. i'm just summarizing some of what i have picked up along the way. if somebody with more experience in the physics/chemistry, please chime in.