XM24A1
An experimental variant re-chambered for the .300 Winchester Magnum (7.62×67mm) round. It was not adopted by the US Army due to concerns that operatives in the field would not be able to acquire the special ammo. Also, the available .300 Winchester Magnum ammo that was procured sometimes misfired due to incompletely-burned propellant in the longer cartridge.
M24A2
Remington has developed an improved version of the M24 rifle, known as the M24A2. The A2 model features a detachable 5-round magazine, top-mounted and adjustable side-mounted Picatinny rails (advertised by Remington as "MARS", or Modular Accessory Rail System), barrel modifications designed to accommodate a sound suppressor, and an improved H-S Precision PST-026 stock with adjustable cheek height and length of pull. Existing M24s can also be converted into M24A2s, which replaces the stock and adds the new detachable magazine feed. The conversion requires a re-barreling of the weapon so it can take the OPS silencer.
M24A3
Remington developed the M24A3 SWS, a variant of the M24 chambered for the .338 Lapua Magnum round (8.58×70mm) and feeding from a 5-round detachable box magazine. It comes tapped for the Leupold Mk 4 M1LR/T 8.5–25×50mm Variable Power day scope. It can also use detachable front and rear Back-Up Iron Sights in an emergency (BUIS units are standard accessories that can be fitted to the Picatinny Rail that runs on the top of the receiver and along the barrel).
U.S. Army 2009 solicitation for an M24 reconfiguration
The U.S. Army put out a solicitation in May 2009 for reconfiguring M24 Sniper Weapon Systems currently available in Army inventory consisting of a:
*Rebarreling/rechambering the SWS's barrel optimized to accommodate Mk 248 (DODIC A191) .300 Winchester Magnum ammunition.
*Replacement of existing weaver rails with a MIL-STD-1913 rail capable of accommodating both a day optic and in-line forward mounted, AN/PVS-26 (NSN 5855-01-538-8121) image intensified (I2) night vision device.
*Reconfiguring the stock with a stock that incorporates a detachable box magazine, adjustable comb and length of pull.
*Addition of a detachable sound suppressor as well as any necessary barrel modifications required for a sound suppressor interface.
*Replacement of the existing day optic sight (DOS) and rings with an Army specified variable power day optic and compatible rings.
The US government purchased MK 248 MOD 1 .300 Winchester Magnum match-grade ammunition in 2009 for use in .300 Winchester Magnum sniper rifles like the U.S. Navy Mk.13 MOD 5 rifle or reconfigured M24 SWSs. This ammunition was developed as a .300 Winchester Magnum Match Product Improvement (PIP) and uses the 14.26 g (220 gr) Sierra MatchKing Hollow Point Boat Tail (HPBT) very-low-drag bullet fired at a nominal muzzle velocity of 869 m/s (2,850 ft/s) ± 15.2 m/s (50 ft/s). According to the U.S. Navy this ammunition should increase the maximum effective range of .300 Winchester Magnum sniper rifle systems to 1,370 m (1,500 yd), decrease wind deflection on bullets in flight and use a reduced muzzle flash propellant that remains temperature stable across an operational temperature range of −32 °C to 74 °C (−25 °F to 165 °F). According to JBM Ballistics, using the G7 ballistic coefficient provided by Bryan Litz, the Mk 248 MOD 1 .300 Winchester Magnum cartridge, when fired at its nominal muzzle velocity of 869 m/s (2,850 ft/s), should have approximately 1,286 m (1,406 yd) supersonic range under International Standard Atmosphere conditions at sea level (air density ρ = 1.225 kg/m3).
2010 M24E1 Enhanced Sniper Rifle reconfiguration competition
In September 2010 the United States Army's Joint Munitions and Lethality Contracting Center awarded Remington a Firm Fixed Price Indefinite Delivery/Indefinite Quantity contract (W15QKN-10-R-0403) for the upgrade of up to 3,600 M24 Sniper Weapon Systems currently fielded to the Army pending type classification as the M24E1 Enhanced Sniper Rifle (ESR). Later the Enhanced Sniper Rifle was classified as the XM2010. The major configuration change for this system is the conversion from 7.62×51mm NATO to dimensionally larger .300 Winchester Magnum ammunition exploiting the M24's "long action" bolt to provide additional precision and range.
IDF modernized M24
In 2019 the Israel Defense Forces started to upgrade the M24 and replace the stock and receiver of the old M24 rifles with a modern stock with AR15/M16 pistol grip, adjustable stock, magazine feeding and Picatinny rails around the barrel.
