bennedose wrote:Having said that, if one wants to be a physics Nazi then two additional points must be taken into account:
"Physics nazi"? It seems to me that discussing the scientific aspects of a matter like this cuts to the heart of the discussion, and is hardly regarded correctly as a minor detail of ballistics.
bennedose wrote:1. The minute you replace any proportion lead with an equal volume of steel in a bullet, the lower specific gravity of steel ensures that the bullet will inevitably be lighter (have less mass) than a pure lead bullet. A lighter bullet in turn wil inevitably exit with a higher muzzle velocity given the same propellant energy.
This is true, but not a relevant issue. Lead is about 50% more dense than steel. Are we discussing projectiles that weigh 33% less than normal lead bullets? No. We are discussing bullets of approximately the same weight, which means that the steel-cored bullet must be larger, and if of the same bore, this means longer.
A longer bullet means that it will have more drag, thus slow down faster than a more compact one, given that the compared bullet designs have similar drag. A more dense bullet will retain energy better at longer ranges. So, for short range (given that the steel cored bullet will be of about the same weight as the lead core bullet), there will not be a significant difference between the energy of steel core vs. lead core bullets. (Actually, the steel core bullet, being longer, may experience somewhat more friction in the barrel.)
Because the steel core bullet is not as dense, it must be loaded to a longer length than a lead bullet (taking up more room in the magazine) or it must be loaded deeper in the cartridge case, taking up volume that could be used for powder/propellant.
2. Since steel is more resistant than lead to deformation under stress, a steel core bullet is less likely to flatten out as much as a pure lead bullet leading to dissipation of energy over a larger area. A concentration of the same energy over a smaller area means higher penetration.[/quote]
Steel may be more resistant to lead under stress, but this is not quite as straightforward as it seems. First of all, steel cores used in bullets are not "tool steel," they are soft steel. The steel is not normally treated, as this costs money. Steel cores meant specifically for armor piercing may have alloys that make them able to penetrate more deeply, but this is not the case for normal rounds, where the cost savings of using steel cores is commonly one of the advantages of using this material for bullets. The Soviet Union, for example, used steel core bullets, as well as copper-washed steel jackets in order to conserve copper-based alloys for other war uses. (They used steel cartridge cases for the same reason.)
Lead used in bullet cores is not normally pure lead, such as what is used in muzzle loading weapons, either, and the lead is coated with a copper alloy jacket (or steel) which gives rigidity to the bullet, as well.
Early French Lebel ammunition used bronze as a bullet material and some hunting bullets that are meant for deep penetration of tough game also are solid, without the use of lead. However, on the other hand, US A10 attack aircraft used a special 30mm cannon using rounds with bullets made of cores of depleted uranium, giving even greater density and energy retention for punching holes in armored vehicles on the battlefield.
This subject is more complex that is being presented and the issues involved are hardly worthy of blithe dismissal as irrelevant.