While initial media briefs on the systems set to replace the M4 Carbine and M249 SAW on the Army's frontlines held back some details, the specs are now public. 

The largest and most sweeping small arms program developed by the U.S. military since the 1950s, the Next Generation Squad Weapon initiative recently picked Sig Sauer to provide the XM5 rifle and XM250 light machine gun to replace the M4 and M249, respectively. Both weapons use Sig's in-house developed SLX suppressor system and 6.8x51mm cartridge-- sold on the consumer market as the .277 Sig Fury. Meanwhile, the platforms will use an integrated optics system developed for the purpose by Vortex. 

A briefing by the Army last month immediately after the announcement that Sig was the tentative winner to supply the XM5 and XM250 was fuzzy when it came to weights and dimensions. 

"So, I -- so the weights are -- I'll give a comparison to the M4 and the 249 in general weight difference," said Col. Scott Madore, PM Soldier Lethality. when asked. "So, the rifle -- the Next Gen Squad Weapon rifle is about two pounds over the M4. Now the automatic rifle is actually four pounds less than the current M249 squad automatic weapon."

Now the Army has released the figures, with the XM5 listed as 8.38 pounds, and 9.84 with its suppressor attached. The overall length, with suppressor attached, is 36 inches with the side-folding stock extended and the standard 15.3-inch barrel. By comparison, the service lists the weight of the M4A1, complete with backup iron sight, sling, adapter rail system, and an empty magazine, as 7.74 pounds. Length of the M4A1 with its stock extended and without a suppressor is 33.82 inches. 

 

XM5 Sig Sauer MCX Spear
The NGSW-R, the XM5 rifle, is Sig Sauer's MCX Spear. Using a 20-round magazine, it is chambered in a new 6.8x51 caliber. (Photo: Chris Eger/Guns.com)

 

When it comes to the expected ammo load carried with the rifle, as the XM5 uses a larger and more capable cartridge than the 5.56 NATO caliber platform it is replacing, and thus uses 20-round magazines instead of the 30-rounders standard with the M4 series, the XM5 basic combat load is seven, 20-round magazines-- or 140 rounds-- which weighs 9.8 pounds. Of note, this is more weight for fewer rounds compared to the current standard, as the M4 carbine combat load, which is seven 30-round magazines-- for 210 rounds-- weighs 7.4 pounds.

The recently disclosed figures on the XM250 detail it is 41.87 inches long with the suppressor attached on the standard 17.5-inch barrel and weighs 13 pounds with a bipod and 14.5 with the suppressor. The most recent training manual on the M249 lists it as weighing 15.16 pounds with bipod and running some 40.87 inches long. 

 

XM250 Sig Sauer machine gun NGSW-AR
The XM250, Sig Sauer's light machine gun, is the tentative NGSW-AR winner. Like the XM5, it is chambered in 6.8x51mm. It is expected to replace the M249 SAW in front-line service with the U.S. Army. (Photo: Chris Eger/Guns.com)

 

Like the combat load of the XM5 compared to the M4, the XM250 user will carry fewer rounds at a heavier weight, described as four 100-round pouches, at 27.1 pounds. The M249 light machine gun combat load, which is three 200-round pouches, weighs 20.8 pounds.

Is the juice worth the squeeze? The Army thinks so, saying the benchmark for the 6.8 cartridge was that it weigh less per round than the 7.62 NATO.

 

Throwback comparison

 

With that in mind, in a very real sense, comparing the XM5/XM250 to the M4/M249 is an apple to oranges situation, and it may be more appropriate to journey back to about 1965 and compare the new guns to the M14 battle rifle and M60 machine gun, both of which were in 7.62. 

The basic wood-stocked M14 hit the scales at 9 pounds empty and was, initially, carried with five 20-round magazines, later increased to seven mags. A 140-round combat load of 7.62 carried in seven steel M14 mags is 11.2 pounds, or about 1.5 pounds less than the same quantity of 6.8 as carried with the XM5.

 

M14 demo at Fort Dix in June 1959
A demo of the then-new M14 at Fort Dix in June 1959. Similar in size to the M1 Garand, with 29 of 116 parts interchangeable with that .30-06 semi-automatic rifle, the M14 was select-fire and had a larger, 20-round magazine. (Photo: Springfield Armory National Historic Site) 

 

The M60, which was often derided as "The Pig" due to its weight, took cues from the German MG42 machine gun and, even with the use of early plastics in its furniture, weighed 23 pounds when introduced, although this was later whittled down to a more carry-friendly 18.5 pounds, both figures significantly heavier than the XM250. 

 

M60 Demo Fort Dix
A demo of the then-new M60 before troops. The 23-pound 7.62 NATO belt-fed machine gun replaced the awkward M1919A6 and was considered much lighter than the latter 32-pound weapon, so much so that it was demonstrated firing one-handed overhead. (Photo: Springfield Armory National Historic Site) 

 

As noted by the Army, "The 6.8 mm has proven to outperform most modern 5.56mm and 7.62mm ammunition against a full array of targets."
 

revolver barrel loading graphic

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