One of the primary controversies today is lead in bullets. There is much discussion about lead in bullets and the possible impact on wildlife health from leaded bullets. As a lead core bullet expands it loses some fragmentation. The game that eludes the hunter but dies or viscera that is left after dressing out the game and scavengers then take in the lead fragments as they feed. Vultures, wolves, bears and coyotes that take advantage of carrion are ingesting the lead causing health problems. There have been no studies or other scientific evidence to back the theories. California has mandated lead free projectiles and Arizona has voluntary compliance.
Lead Cored Bullets VS Copper Ballistics
Lead is still viable in other states so conventional projectiles are allowed. First let us consider that there is no economical or performance advantage to other lead-free alternatives. Most alternatives are based on a solid copper projectile. These are a bit more expensive than are lead-cored bullets. To reach the same projectile weight necessitates a longer bullet. The longer the bullet relative to the bore size the tighter the rifling twist must be. Since all copper bullets are less dense than the lead core bullets and the solid copper deforms less the solids increase friction in the bore and don’t accelerate as fast. Terminal hits with lead cored bullets have increased weight, therefore the they have increased momentum, are more stable bucking the wind, retain higher velocity, penetrate deeper and tend to be more accurate. Given the same dimensions as a lead-cored bullet the all copper will be lighter, it will have lower momentum and the velocity will drop off faster due to the lower cross-sectional density. To compensate the bullets are longer to retain weight but offer a broader profile to the wind, affecting accuracy. So, given the same bullet length the lead-core bullet will retain more velocity and penetrate deeper than an all copper bullet. Lighter bullets should have a higher muzzle velocity, but because of the harder solid surface of the all copper bullet there is less acceleration due to friction without higher chamber pressures. Though muzzle velocity is perhaps a little higher it is not in relationship to a lead core bullet and the gains do not compensate for faster deceleration of the bullet in flight.
Penetration of Copper Bullets
Penetration is affected as well. To kill you need to penetrate deep causing cardiovascular damage to capillaries, veins and arteries, or disrupt the central nervous system. To get to the organs and skeletal structure you need good penetration with bullet expansion. Solid copper bullets are good penetrators, perhaps too good. Even with expansion the bullet retains weight better than a lead-cored bullet. The expansion with copper is more symmetrical as well as allowing a straighter drive into the tissue. They are much less prone to fragmentation.
Fragmentation of Lead Cored Bullets
The problem with lead-cored bullets is that some can loose up to 35% of their weight to fragmentation that is scattered through the meat around the wound channel. The meat is either discarded or consumed by people or scavengers. Many of these factors are nullified by using premium lead core bullets. Factors affecting fragmentation are:
• Velocity in excess of 2,000 fps. This means rifle velocities.
• Light bullets for caliber fragment more than do the heavier bullets.
• Bullet designed for a fast expansion rate on impact. Soft points or ballistic tipped bullets.
• If the jacket and core are fused together the lower fragmentation rate, some as low as 5% weight loss. Bonded, core lock etcetera.
• Bullet fragmentation is higher with hits to skeleton particularly shoulder and pelvis hits into dense heavy bone.
Cost from Switching from Lead to Copper Bullets
Solid copper is about 30% more than lead bullets. Part of this is perhaps related to scale. Far more bullets have lead cores versus the solids. With higher production rates the cost may fall somewhat. Another aspect of cost is the wear and tear on the gun. Harder bullets erode and wear down the gun faster, particularly in the barrel’s throat area. Lead core bullets are softer. Yes, the jackets are copper but are relatively thin and the lead core accommodates deformation better than a solid copper bullet. The plus side is that most hunters shoot relatively few rounds and thus the guns last much longer than a competitor who shoots up to a thousand rounds a month. The military has adopted a leadless bullet made with a copper alloy body and a steel penetrator at the tip. The big question is rimfire. It has proven problematic to get a decent solid non-lead projectile for .22 Shorts and Long Rifle. The magnums and the .17 rimfires already fire jacketed bullets. But these are not ‘heeled’ like the venerable .22 where the bullet is the same diameter as the case. A dilemma for sure.