The 6.5×43 LICC

Yesterday I posted about how FN USA had entered into a long-term development contract with the Department of Defense’s Irregular Warfare Technical Support Directorate (IWTSD) which included development of a rifle and machine gun using a 6.5x43 LICC round. A reader commented that there wasn't much information about the ammunition itself, so I did a bit more sleuthing.

    An article from Guns.com from 2023 ("FN Shows off New 6.5x43 Individual Weapon System") noted that the cartridge had previously been known as the .264 USA and linked to a 2014 article at The Firearm Blog by Nathanial H. ("The US Army Marksmanship Unit's .264 USA"). For those of you that weren't reading TFB content from that far back, Nathanial H. was a ballitician that provided some very technical content. He eventually was hired by one of the firearms or ammo companies and stopped writing. 

    In any event, he provides a diagram and dimensions of the cartridge (although at that time it was still a brass cartridge--the Guns.com article provides more detailed photos of the steel case). He also mentions that "[t]he RFP linked above specifies that the .264 USA be capable of producing 2,875 ft/s with a 107gr lead-cored Sierra HPBT from a 16.7″ barrel, or 2,657 ft/s with a 123gr Sierra from the same length." However, the RFP concerned a case employing a polymer case and thus may not reflect the final steel cased product. Nathanial also commented:

    One of the schools of thought that has gained some ground within the Army itself is the idea of a “general purpose round”, a proposal to replace the current two-caliber system of 5.56mm and 7.62mm ammunition with a single round, usually somewhere in-between those two calibers in size and weight.

    It’s a theory I am highly critical of, but that does not mean it is without merit. The paradigm has definite benefits, and should be investigated even if there is some certainty that, at the moment, it’s not practical or desirable to implement such a scheme. So it’s right that the Army Marksmanship Unit has endeavored to produce and test a round that could fulfill such a role, called the .264 USA. The round is a 6.5mm caliber round, based on lengthened 7.62×39 brass, with very little case taper (0.26 degrees, almost half that of 5.56’s 0.5 degrees, and still considerably less than 7.62x51mm’s 0.35 degrees) but a very slender 17.5 degree shoulder. At 2.6″ long, the .264 USA is closer to 7.62mm than 5.56mm in size and weight, but it nonetheless would afford slightly smaller and lighter weapons and magazines. ...

Nathanial authored a companion article in 2016 ("Modern Intermediate Calibers 021: The US Army Marksmanship Unit's .264 USA") that discusses the ballistics of the .264 USA in much more detail but, again, was before the development of the final steel cased version. 

    A 2023 article from the Armourer's Bench ("FN’s Individual Weapon System in .264 USA") has some more information on the projectiles tested for the cartridge at that time (by which time the polymer case had been abandoned for the steel case) and relates:

    ... The 6.5x43mm round uses a steel case, which FN America says reduces weight by 20% compared to equivalent brass. No data on velocities has been released yet. The round has a two-piece, lightweight steel design with a stainless steel head and case body. A variety of loads have been developed with a number of different projectiles, including a 130gr Reduced Ricochet Limited Penetration round, a 109gr copper open tip match (OTM), a 120gr copper OTM and a soft nose 125gr cartridge. To date FN haven’t yet released any data on the rounds  performance.

    According to the 2019 Broad Agency Announcement (BAA), which outlined the programme’s requirements, polymer cased ammunition was considered and two proof of concept rounds were desired for Phase 1: 108gr OTM with a muzzle velocity of 2650 feet per second, from an 11.5 inch test barrel, and a frangible training round.

    In Phase 2 IWTSD required Combat Barrier rounds loaded with Special Operations Science and Technology (SOST-style) projectiles and an M855A1-style enhanced penetration round which could penetrate no less than 12-inches of 10% ordnance gelatin at 800m and no greater than 18 inch at 25m-150m when fired from a 14.5 inch barrel or 25m-450m when fired from a 11.5 inch barrel.

 This article also has more information about the individual weapons--a CQB carbine, standard carbine, and RECCE rifle--including weights. See also "FN America (FNA) Previews the Lightweight Intermediate Caliber Cartridge (LICC) Individual Weapon System (IWS) Developed for the Irregular Warfare Technology Support Directorate (IWTSD)" and "FN Delivers Weapon System Test Samples to DoD’s Irregular Warfare Technical Support Directorate" both from Soldier Systems which has more information about the weapons. 

    Undoubtedly the steel cased versions probably use a higher pressure than detailed in Nathanial F. articles, but his articles probably give a good indication of the performance of the cartridge.