Editing Terminal ballistics (section)

==== Lead ====
Malleable lead alloy or jacketed lead core projectiles conducive to expansion have been shown to be capable of exhibiting between 98 and 100% weight retention at velocities up to 2000 feet per second, however measures approaching an ideal weight retention in practice would generally be realized at lower velocities due to inconsistencies of impacted targets in the real world.  According to various experience and methodology, the limit at which expanding lead projectiles of appropriate alloy can be launched with minimal contamination upon impact may be contended more or less within the vicinity of [[Mach number|Mach]] 2 speeds. 

Several methods have been developed to improve performance under the stress of high velocities.  Hard cast lead alloys have been utilized which are resistant to expansion and deformation of any kind.  These hard cast varieties may be more brittle than softer alloys, but within their limitations are capable of exhibiting greater weight retention at velocities up to around 2500 feet per second.  Whether or not they are of sufficient construction, cast lead bullets are typically not pushed at significantly higher velocities, as accuracy is subject to degrees of degradation, with relation to the type of alloy, form of the bullet, lubricants or coatings, and design of the barrel.  

Bullets with an exposed lead tip which are designed to fire in excess of 2400 feet per second are typically made of a jacketed variety, encased in copper, brass, or iron/steel.  There is less tolerance for gaps in understanding brought by research and development above the ordinary threshold of velocity for lead bullets.  To mitigate significant material loss, the jacket of bullets may be bonded intricately to the lead core at a molecular level, typically by thermal adhesion or [[Electrochemistry|electrochemical]] processes.  It is generally acknowledged that bonded bullets are capable of increased resilience under severe [[Stress (mechanics)|stress]].  Depending on experience and methodology exemplary bullets can be observed which are theoretically capable of optimal weight retention under the hydraulic forces of impact velocities roughly in the vicinity of 2300 to 2700 feet per second.  Designs with more reactive expansion characteristics may exhibit optimal weight retention at much lower velocities.  Above their optimal threshold, bonded bullets with resilient alloys and construction may perform diminishing yet remarkable returns for weight retention, where standard jacketed varieties circumstantially exhibit the risks brought by severe loss of integrity, which manifests to various effect. <ref>{{Cite journal |date=August 2023 |title=Weight retention and expansion of popular lead-based and lead-free hunting bullets |doi=10.1016/j.scitotenv.2023.166288 |last1=McTee |first1=Michael |last2=Parish |first2=Chris N. |last3=Jourdonnais |first3=Craig |last4=Ramsey |first4=Philip |journal=Science of the Total Environment |volume=904 |doi-access=free |pmid=37586537 }}</ref>

Additionally, the shape of the jacket material may be designed to mechanically retain a lead core to prevent the bullet from severely separating.  This can be accomplished either by completely compartmentalizing separate sections of the bullet, or by a retaining shelf on the interior meant to lock the lead core into place to ensure a sufficient degree of the softer core can be reinforced by a stronger metal as it deforms.  Such construction does not alter the limitations of a given alloy, but can allow for designs with highly reactive expansion characteristics in a given circumstance to retain sufficient mass for some length of penetration, even when significant loss of material is to be expected.