The Marine Corps is looking to retire two famous weapons systems that it has used since the Vietnam War in favor of sniper rifles and carbines first adopted by the U.S. Army.

The M40 family of bolt-action rifles was born in the Vietnam War when the Corps decided there was a need to standardize sniper rifles. The Remington 700-based 7.62 NATO-chambered rifle has evolved slowly through a number of minor chassis, optic, and barrel changes over the past five decades which enhanced its accuracy, but never extended its range beyond the 1,000 yards± practical limitations of the 7.62×51 NATO cartridge.

The Marines are looking to address that range deficiency, and while they have made no official statements on what their next sniper rifle will be, the current down-sizing of the military and a push for standardization suggests that the smart bet is on the adoption of the next-generation multi-caliber Remington sniper rifle system now being used by the U.S. Army, the Mk.21 PSR:

The Marine Corps is looking to field a new sniper rifle, but has yet to identify what type and caliber, according to a Marine spokesman.

“We are looking at a number of available options, to include the Mk.21 Precision Sniper Rifle,” said Maj. Anton Semelroth in an e-mail. “The Marine Corps continues to evaluate the need for improved capabilities for our snipers and to consider solutions being pursued by the Army, other services and [Special Operations Command].”

The current rifle, the M40A5, has an effective range of around 1,000 yards and fires a .308 caliber bullet. The Mk.21, on the other hand, can be fitted to fire a .338 caliber bullet and hit targets at more than 1,600 yards. The Mk. 21 is also currently in use by various special operations units.

The Mk.21—or Modular Sniper Rifle as it is known within Remington Defense—can swap between four calibers (.338 Lapua Magnum, .338 Norma Magnum, .300 Winchester Magnum, 7.62×51) for different missions, and would almost double the practical engagement range for Marine snipers. Another possible contender to replace the M40A5 is yet another Remington 700-based sniper rifle used by the Army, the .300 Winchester Magnum-chambered M2010, which is replacing the Army’s M24 sniper rifles.

Either system will be a significant improvement on the range limitations of the 7.62×51 NATO cartridge.

Marine infantry will also be looking to adopt Army-proven hardware as well, as they shift away from the long-serving M16 rifle series to the more compact M4 carbine.

Marine leaders have made the momentous recommendation to ditch the iconic M16 in favor of the M4 carbine as the new universal weapon for infantrymen.

The recommendation to swap the venerated rifle that has served as the grunt’s primary implement of war since Vietnam now sits on the commandant’s desk, pending his final review and a decision. But, the swap appears imminent and if approved will relegate the M16 to a support role. It follows a similar shift already underway in the Army.

With the endorsement of several major commands already supporting the switch — including Marine Corps Combat Development Command; Combat Development and Integration; Plans, Policies and Operations; Marine Corps Systems Command; and Installations and Logistics — final word is possible in weeks or months.

Some velocity and range will be lost if the Corps shifts to the M4, but it’s hoped that the newly adopted M27 Infantry Automatic Rifle (IAR)—which doubles as a designated marksman’s rifle due to its accuracy—will help mitigate that deficiency.

7/31/2015 Update: The Marines will not be transitioning to a modern sniper rifle, but will instead upgrade the M40A5 to the M40A6, not wanting to spend the money on the tools their sniper’s need.