View source for 6.8x43mm LUDC

{{Infobox firearm cartridge
| name = 6.8x43mm LUDC
| image = 6.8_SPC_+_223.jpg
| image_size = 300px
| caption = 6.8x43mm LUDC (left), 5.56×45mm LOTA (right)
| origin = {{flag|Burgundie}}<br>{{flag|Urcea}}<br>{{flag|Yonderre}}
| type = {{wp|Rifle}}, {{wp|carbine}}, {{wp|Designated marksman rifle|DMR}}, and {{wp|Light machine gun|LMG}}
| used_by = [[Levantine Union Defense Council|LUDC]]<br>Non-LUDC allies<br> See ''[[#Users|Users]]''
| wars = [[Final War of the Deluge]]
| design_date = late 2010s
| designer = 
| service = 2018–present
<!-- Specifications -->
| parent = 7.62x51mm LOTA
| case_type = Rimless, bottlenecked
| bullet = 0.277
| land = {{convert|0.270|in|mm|abbr=on}}
| neck = 0.306
| shoulder = 0.402
| base = {{convert|0.422|in|mm|abbr=on}}
| rim_dia = 0.422
| rim_thick = 0.049
| case_length = {{convert|1.687|in|mm|abbr=on}}
| length = {{convert|2.260|in|mm|abbr=on}} 
| case_capacity = 34.8-36.9
| rifling = 
| primer = Large Rifle
| max_pressure = 58700
| pressure_method = C.I.P
| max_pressure2 = 55000
| pressure_method2 = SAAMI
<!-- Ballistic performance -->
| velocity = 
| energy = 
<!-- Ballistic data, load 1 -->
| bw1 = 7.45 {{wp|Gram|g}} (115 {{wp|Grain (unit)|gr}})
| btype1 = Full Metal Jacket
| vel1 = 2575
| en1 = 1694
<!-- Ballistic data, load 2 -->
| bw2 = 7.78 {{wp|Gram|g}} (120 {{wp|Grain (unit)|gr}})
| btype2 = Super Shock Tip
| vel2 = 2460
| en2 = 1612
<!-- Ballistic data, load 3 -->
| bw3 = 7.1 {{wp|Gram|g}} (110 {{wp|Grain (unit)|gr}})
| btype3 = Game Hunter
| vel3 = 2500
| en3 = 1525
|bw4=5.5 {{wp|Gram|g}} (85 {{wp|Grain (unit)|gr}})
|btype4=Enhanced penetrator
|vel4=3070
|en4=1780
<!-- Ballistics data source -->
| balsrc = 
}}

The '''6.8x43mm LUDC''', also sometimes '''6.8 LUDC''' and '''.277 LUDC''', is a rimless bottlenecked intermediate rifle cartridge that was developed jointly by [[Burgundie]], [[Urcea]] and [[Yonderre]] to replace the {{wp|7.62x51mm NATO|7.62x51mm}}, {{wp|5.56x45mm NATO|5.56x45mm}} and [[7.5×42mm Yonderian|7.5x42mm]] cartridges used by the three nations respectively in short barreled rifles (SBR) and infantry carbines. Adopted as the official cartridge of the [[Levantine Union Defense Council]] by way of its [[Levantine_Union_Defense_Council#Unified_Operations-Logistics_Initiative|logistics and caliber-streamlining project]], the 6.8x43mm LUDC has been at least partially adopted by all member states of the LUDC.

Originally developed to streamline logistics between the three [[Levantia and Odoneru Treaty Association|LOTA]] allies [[Burgundie]], [[Urcea]] and [[Yonderre]], the 6.8x43mm cartridge is a compromise between the {{wp|7.62x51mm NATO|7.62x51mm LOTA}} cartridge used by the [[Burgoignesc Security Forces]] and the {{wp|5.56x45mm NATO|5.56x45mm LOTA}} used by the [[Armed Forces of the Apostolic Kingdom of Urcea|Armed Forces of Urcea]]. The compromise between the two allows for improved lethality compared to the Urcean 5.56 cartridge, delivering 44% more energy on target, while producing less recoil than the Burgoignesc 7.62 cartridge. Another advantage of the 6.8mm cartridge compared to the 5.56mm is its much higher muzzle velocity, making it considerably more effective out of carbines and short barreled rifles. Four principal types of ammunition are made officially (full metal jacket, full metal jacket tracer, super shock tip and enhanced penetrator) as well as a number of commercial offerings. 

One problem with the 6.8x43mm cartridge in Yonderian service has been its similar dimensions to the [[7.5×42mm Yonderian|7.5x42mm]] cartridges used by the [[Yonderian Defence Force]]. This allows 6.8mm ammunition to be chambered in 7.5mm rifles like the [[FAMAG]] and vice versa; while a 6.8mm bullet will be able to exit the barrel of a 7.5mm FAMAG (most likely causing damage to the rifling), a 7.5mm bullet will not be able to exit a 6.8mm barrel, since the bullet is larger in diameter than the bore. Firing a 7.5mm cartriddge in a 6.8mm gun thus causes excessive pressure to build up since the bullet has nowhere to go, which can cause the rifle to explode resulting in risk of injury or death. Whether a 7.5mm cartridge actually is able to chamber in a 6.8mm barrel depends on bullet length and shape, bullet seating depth, crimping, and the volume of powder charge. Because of this danger, the [[Yonderian Defence Force]] changed its production of 7.5mm ammunition to have longer projectiles in 2021 following a number of incidents.

==Users==
* {{flag|Anglei}}
* {{flag|Bulkh}}
* {{flag|Burgundie}}
* {{flag|Chenango Confederacy}} - supplied by [[Urcea]]
* {{flag|Copake}} - supplied by [[Urcea]]
* {{flag|Fiannria}}
* {{flag|Hollona and Diorisia}}
* {{flag|Kandara}} - supplied by [[Bulkh]]
* {{flag|Lapody}}
* {{flag|New Harren}} - supplied by [[Yonderre]]
* {{flag|Nysdra Provisional Republic}}
* {{flag|Rhotia}}
* {{flag|Tapakdore}} - supplied by the [[Burgo-Darian Mercantile Port Corporation]]
* {{flag|Unnuaq Mission State}} - supplied by [[Urcea]]
* {{flag|Urcea}}
* {{flag|Yanuban}} - supplied by the [[Burgo-Darian Mercantile Port Corporation]]
* {{flag|Yonderre}}

===Non-state users===
* [[File:EI_Logo.png|18px]] [[Intrepid Enterprises]]

===Former users===
* {{flag|Varshan}} - used captured examples during the [[Final War of the Deluge]]

==Weapons chambered for 6.8x43mm LUDC==
* [[FAMAG]]
* [[SAR-99#SAR-99L|SAR-99L]]

==See also==
* [[7.5x42mm Yonderian]]

[[Category:Military technology]]
[[Category:Military]]
[[Category:Weapons]]
[[Category:Levantine Union]]
[[Category:Armed Forces of Urcea‎]]
[[Category:Burgoignesc Security Forces]]
[[Category:Yonderian Defence Force]]
[[Category:Burgundie]]
[[Category:Urcea]]
[[Category:AMY]]
[[Category:Yonderre]]
[[Category:IXWB]]