Editing AK-74 (section)

===5.45×39mm cartridge===
{{Main|5.45×39mm}}
[[File:AK-74 5.45x39mm wound ballistics.gif|thumb|left|AK-74 5.45×39mm wound ballistics]]

Relatively small sized, light weight, high velocity military service cartridges like the 5.45×39mm allow a soldier to carry more ammunition for the same weight compared with their larger and heavier predecessor cartridges, have favourable maximum [[point-blank range]] or "battle zero" characteristics and produce relatively low [[bolt thrust]] and [[free recoil]] impulse, favouring light weight arms design and automatic fire accuracy.<ref>{{cite web |url=http://www.quarryhs.co.uk/Assault.htm |title=Assault Rifles and Their Ammunition: History and Prospects |first=Anthony G. |last=Williams |date=November 2014 |website=Military Guns & Ammunition |access-date=16 November 2014 |archive-url=https://web.archive.org/web/20171105042707/http://quarryhs.co.uk/Assault.htm |archive-date=5 November 2017 |url-status=live}}</ref> Tests measured the free recoil energy delivered by the 5.45×39mm AK-74 rifle at {{convert|3.39|J|ftlb|abbr=on|2}}, compared with {{convert|7.19|J|ftlb|abbr=on|2}} delivered by the 7.62×39mm in the AKM.<ref>{{cite web |url=http://www.thefreelibrary.com/The+Russians+are+coming!+The+Russians+are+coming!+Or+maybe+the+Polish.-a0182033227 |title=The Russians are coming! The Russians are coming! Or maybe the Polish |first=Holt |last=Bodinson |work=[[Guns (magazine)|Guns]] |date=1 September 2008 |access-date=16 November 2014 |via=The Free Library |archive-url=https://web.archive.org/web/20141020151119/http://www.thefreelibrary.com/The+Russians+are+coming!+The+Russians+are+coming!+Or+maybe+the+Polish.-a0182033227 |archive-date=20 October 2014 |url-status=live}}</ref>

Early 5.45×39mm ballistics tests demonstrated a pronounced tumbling effect with high speed cameras.<ref>{{cite journal |url=http://findarticles.com/p/articles/mi_qa3912/is_200112/ai_n9010648/pg_3 |title=Terminal ballistics of the Russian AK 74 assault rifle: Two wounded patients and experimental findings |first1=Želimir |last1=Korać |first2=Dubravko |last2=Kelenc |first3=Danko |last3=Mikulić |first4=Dragan |last4=Vuković |first5=Janko |last5=Hančević |name-list-style=amp |doi=10.1093/milmed/166.12.1065 |journal=[[Military Medicine (journal)|Military Medicine]] |volume=166 |issue=12 |pages=1065–1068 |date=December 2001 |pmid=11778406 |access-date=2007-09-25 |archive-url=https://web.archive.org/web/20080310025623/http://findarticles.com/p/articles/mi_qa3912/is_200112/ai_n9010648/pg_3 |archive-date=2008-03-10 |url-status=dead|doi-access=free }}</ref> Some Western authorities believed this bullet was designed to tumble in flesh to increase wounding potential. At the time, it was believed that [[flight dynamics|yawing]] and [[cavitation]] of projectiles were primarily responsible for tissue damage. [[Martin Fackler]] conducted a study with an AK-74 assault rifle using live pigs and [[ballistic gelatin]]; "The result of our preset test indicate that the AK-74 bullet acts in the manner expected of a full-metal-cased military ammunition – it does not deform or fragment when striking soft tissues".<ref>{{cite journal |url=http://ammo.ar15.com/project/Fackler_Articles/ak74_wounding_potential.pdf |title=Wounding Potential of the AK-74 Assault Rifle |first1=Martin L. |last1=Fackler |first2=John S. |last2=Surinchak |first3=John A. |last3=Malinowski |first4=Robert E. |last4=Bowen |name-list-style=amp |journal=[[The Journal of Trauma]] |date=March 1984 |volume=24 |issue=3 |pages=263–266 |doi=10.1097/00005373-198403000-00014 |pmid=6708147 |access-date=2007-09-25 |archive-url=https://web.archive.org/web/20090219104944/http://ammo.ar15.com/project/Fackler_Articles/ak74_wounding_potential.pdf |archive-date=2009-02-19 |url-status=dead}}</ref> Most organs and tissue were too flexible to be severely damaged by the temporary cavity effect caused by yaw and cavitation of a projectile. With the 5.45&nbsp;mm bullet, tumbling produced a temporary cavity twice, at depths of {{convert|100|mm|abbr=on|1}} and {{convert|350|mm|abbr=on|1}}. This is similar to (but more rapid than) modern 7.62×39mm ammunition and to (non-fragmenting) [[5.56×45mm NATO]] ammunition.