U.S. Special Operations Command is working with the same company building the Army’s newest handgun to upgrade the M4A1 rifles commonly used by its joint-service operators.

At the end of July, SOCOM announced it had awarded Sig Sauer a contract for its suppressed upper receiver group, or “SURG,” to pair with the M4′s lower receiver. The five-year, indefinite-delivery and indefinite-quantity, firm-fixed-price contract is worth $49 million, according to a U.S. Defense Department announcement.

The SURG is an upgrade to the current M4A1 Carbine — itself a fully automatic version of the M4 Carbine — that went into service in 1994, according to Sig Sauer’s press release. The majority of the work for the contract will be performed in Newington, New Hampshire, and is expected to be completed by July 2023.

The SURG program was ongoing for the past few years as it worked to produce a weapon for SOCOM operators that cuts the noise from a fired round more efficiently, with fewer problems than what can be provided by simply adding a suppressor and threaded barrel to a standard upper receiver.

Among the competitors, Sig Sauer alone provided a suppressor that withstood the stress and torture requirements set by SOCOM for firing specifications, vibration, sound and temperature requirements to ensure soldier safety.

The suppressed upper receiver group, according to Soldier Systems. (SoldierSystems.net)
The suppressed upper receiver group, according to Soldier Systems. (SoldierSystems.net)

“The requirements set by DOD for the SURG procurement demanded significant improvements in reliability, thermal characteristics, and durability that went well above anything we are currently seeing in the industry,” said Ron Cohen, President and CEO of Sig Sauer, Inc, in a company statement.

“We worked very hard to develop the MCX SURG System to specifically meet and exceed the DoD requirements," he added. "I am extremely proud that our hard work paid off, and endured the stringent and demanding military testing requirements, to ultimately gain the confidence of DoD to support their operations in the field.”

The exact specifications of the SURG are not fully known, but SOCOM previously stipulated that the receiver should be no more than 25.5 inches long, with a barrel that’s at least 11.5 inches long and a total weapon system weighing no more than 7 pounds, according to Soldier Systems, which has followed the contract process closely.

As for performance, SOCOM wanted the M4A1 equipped with a SURG optimized to fire the M855A1 and the MK318 MOD0 / MOD1 cartridges for at least 1,200 rounds without lubrication.

“While the suppressor must be rebuildable, only one component of the suppressor has to be serialized but that part had to last the lifetime of an M4A1 lower receiver (125,000 rounds),” Soldier Systems reported. “The rebuildable components need to last at least 15,000 rounds but SOCOM further challenged industry to make them last for 20,000 rounds.”