Rifle of the world 3 : Mark 12 Mod 0/1 Special Purpose Rifle (SPR) c

Sights: The original SPR used an early PRI flip-up front sight with an elevation dial, which has since been discontinued. The Mk 12 Mod 0 uses the current PRI flip-up front sight. The SPR/A, SPR/B, and Mk 12 Mod 1 use the KAC rail foreend flip-up front sight. The SPR and Mk 12 Mod 0 use the ARMS #40 flip up rear sight. The rest of the models use the KAC 600 meter flip up rear.

Optics: Due to the relative modularity of the system, optics (as well as almost everything else) can be mounted according to the operator's wishes. However, SPRs are most often seen with a 3.5–10×40 mm Leupold LR M3 (SPR/A), a 2.5–9×36 mm TS-30 (SPR/B), or a 3–9×36 mm TS-30 A2 (Mk 12 Mod 0/1) Mid Range/Tactical Illuminated Reticle Dayscope (civilian versions are known as the Leupold Mark 4 MR/T 3–9×36). Night vision devices can also be attached. These scopes usually come with flip open dust covers and a honeycomb anti-glare anti-reflection device (ARD). Given Nightforce Optics' recent NAVSPECWAR contract, it is believed that many NAVSPECWAR issued SPRs will use the Nightforce 2.5-10x24 NXS scope.[2] Mounts: As mentioned before, a long accessory rail, called a SWAN Sleeve (ARMS SPR MOD or ARMS #38 SPR PEQ-2-3), manufactured by ARMS, is installed, running the length of the rifle. The SPR/A and SPR/B both used the KAC M4 Match FF RAS. Two ARMS #22 Throwlever 30 mm steel rings are used to mount the dayscope. The SPR/A, SPR/B, and Mk 12 Mod 1 use ARMS #22 high rings, while due to the increased height from the SWAN Sleeve, the SPR and Mk 12 Mod 0 use ARMS #22 medium rings. An under-the-handguard ARMS #32 Throwlever mount is used to mount the Harris bipod (the ARMS #42 Throwlever mount is used to mount the Versa-Pod); this features a quick release action.

Bipod: Originally Versa-Pods (a cheaper Chinese-made copy of the relatively expensive Parker-Hale swivel bipod) were used, but were taken off the system after the initial SPR. Currently, a Harris swivel model bipod is typically used with the SPR, and is sometimes seen with a KMW Pod-Loc tension adjustment device. As mentioned above, the bipod is mounted via a ARMS #32 throwlever device attached to the bottom rail of the rifle's forearm. The ARMS mount is used on both the Mod 0 and Mod 1.

Suppressor: The OPS Inc. 12th Model SPR Muzzle Brake Suppressor (MBS) threads directly onto the OPS Inc. muzzle brake and uses the collar to stay centered. Ammunition: The SPR is not used to fire standard issue 5.56 x 45 mm NATO M855 ball or M856 tracer ammunition, and especially not M193 ball ammunition. Due to the limits in terminal performance and relatively poor accuracy of the 62-grain (4 g) M855 ball, the Mk 262 Open Tip Match (OTM) round was developed as a more accurate round for the SPR, and manufactured by Black Hills Ammunition. The first production batches were designated Mk 262 Mod 0 and used a Sierra Bullets MatchKing 77-grain (5 g) Hollow Point Boat Tail (HPBT) bullet without a cannelure (crimping groove). Black Hills then approached the Nosler bullet manufacturing company, who made a similar 77 gr (5.0 g) OTM bullet, and Nosler agreed to supply cannelured bullets to Black Hills. The newer load was designated Mk 262 Mod 1. Recently, Sierra agreed to add a minimal crimp to their bullet, and this has since replaced the Nosler bullet in the current versions of Mk 262 Mod 1.