For squad level organization, I support the USMC model. For weaponry, particularly direct fire, I would argue for a baseline of squad level weapons being chambered in 300 Blackout, while granting the squad better access to 7.62x51 weapons based on the mission and environment.

As state-on-state conflict continues to lose utility, training and equipping for the small wars has a greater value than ever. Embodying past, present, and projected future trends, what capabilities should the infantryman’s primary weapon have? Former SEAL and tactical firearms trainer Kyle Defoor advocates that the modern fighting carbine should “be able to shoot effectively at CQB distance, take positive head shots at 100, and engage at the max distance for 5.56 - IMO 400 yds on the body.” By many accounts, practical combat accuracy out to approximately 300-400 yards seems to be the common understanding for the capabilities of an infantryman and his rifle.

Some have taken a look at the relatively new 300 Blackout (7.62x35) as a more ideal caliber due to its better terminal ballistics from shorter barrels, better intermediate barrier performance, acceptable external ballistics for the ranges considered, and better integration with suppressors. It is designed to operate reliably suppressed or unsuppressed, using supersonic or subsonic ammunition. Pairing this extremely versatile cartridge with the extreme versatility of the AR-15 platform is a natural match to arm the infantryman with a more effective weapon. At the squad level, this could materialize as a 7.62x35 service rifles, multiple auto-rifles for volumetric fire, and a squad designated marksman rifle for precision fire. By adding some improvements such as lightweight customizable free-float rail systems, improved triggers, and good optics/lights/lasers, you earn an improved AR-15 family of squad-level weapons ready to dominate at common combat ranges.

What do we give up in terms of capabilities compared to 5.56 chambered service rifles and squad support weapons? In the case of the US Army where current M4 training/qualifications are limited to 300 yards, there is no real change in hit-probability. However, the 400-600 yard ranges where auto-rifles/SAWs and designated marksmen rifles have the capability to reach out is generally outside the envelope of capabilities for 7.62x35. Nevertheless, even with 5.56 support weapons, what we see in Afghanistan is an increasing squad level reliance on 7.62x51 based precision semi-automatic rifles, lightweight variants of the medium machine guns, and essentially heavyweight variants of light machineguns chambered in 7.62x51. To mitigate the shortfalls when compared to 5.56, the theoretical 7.62x35 armed squads would benefit from even better access to 7.62x51 weapons in order to achieve true well-rounded effectiveness from CQB distances to ranges up to 800 yards and beyond. In this sense, the squad designated marksman would be proficient at both 7.62x35 and 7.62x51 chambered precision platforms, and have both available based on the nature of the operating environment and mission at hand. Squad auto-riflemen would enjoy a similar proficiency with 7.62x35 and 7.62x51 chambered fully automatic weapons. Having 2-3 M240s available for use if needed in each squad may sound excessive at first. However, when you consider the mobile patrols in the Iraq War where each HMMWV or MRAP had a crew-served weapon mounted, it seems not so excessive.

Basic breakdown of the two variations:

-Squad Leader

-TL: 7.62x35 carbine
-Auto-rifleman: 7.62x35 auto-rifle OR 7.62x51 medium machine gun
-Squad DM: 7.62x35 carbine OR 7.62x51 DM Rifle
-Grenadier: 7.62x35 carbine +assorted HE weapons

-TL: 7.62x35 carbine
-Auto-rifleman: 7.62x35 auto-rifle OR 7.62x51 medium machine gun
-Rifleman: 7.62x35 carbine
-Grenadier: 7.62x35 carbine +assorted HE weapons

-TL: 7.62x35 carbine
-Auto-rifleman: 7.62x35 auto-rifle OR 7.62x51 medium machine gun
-Rifleman: 7.62x35 carbine
-Grenadier: 7.62x35 carbine +assorted HE weapons

While I think this approach could make for some highly versatile and lethal squads, realistically it will likely be a little while before the US and NATO considers replacing 5.56 with another intermediate cartridge.