From
www.snipercentral.com:
The M25/XM25 is a joint venture sniper rifle, built for both the US Army Special Forces and the US Navy SEALs. It was orginally developed by the 10th SFG base 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, its a National Match M14 glass bedded in a McMillan fiberglass stock, uses a special gas piston, a National Match spring guide and a BPT (Brookfield Precision Tool) Advanced Scope Mounting System. Most rifles use the B&L 10x Tactical scope. Some of the Army rifles use some of the Leupold Ultra MK4 series of scopes. (Both the M3 and M1), and the Navy rifles have been seen with Leupolds also (MK4s and VariX-III LR M3s). Ops Inc suppressors have also been used on some of the rifles.