The M25/XM25 is a joint venture sniper rifle, was built for both the US Army Special Forces and the US Navy SEALs in the late 1980’s. It was originally developed by the 10th Special Forces Group (SFG) based at Ft. Devens in response to a requirement for a match grade M14 for Special Forces sniper teams. USSOCCOM was dubbing the rifle the “Light Sniper Rifle”, and its also known as the “Sniper Security System” and “Product Improved M21”.
The M25 is similar to the M21 in many regards, it is a National Match M14 glass bedded in a McMillan fiberglass stock, uses a special gas piston, a National Match spring guide and a Brookfield Precision Tool Advanced Scope Mounting System (ASMS). Most rifles used the Baush & Lomb 10x Tactical scope though some of the Army rifles used some of the Leupold Ultra MK4 series of scopes. (Both the M3 and M1), and the Navy rifles have been seen with Leupolds as well (MK4s and VariX-III LR M3s). Ops Inc suppressors have also been used on some of the rifles.
The rifle has been referenced as both the M25 and XM25 in US Navy and US Army docs, so I guess the rifle has two official nomenclatures. The M25 is NOT a replacement rifle for the M24, it was requested by the USSOCCOM to fill a specific need, and it served extremely well in the first Persian Gulf war in 1991. The rifle is not officially in use though may still be seen in use with some of the Groups and Teams.