Civilian Marksmanship Program is auctioning XM-3 Sniper Rifle. This was used by DARPA to come up with lighter sniper rifle than M40 while improving accuracy.
Some of the requirements were;
clip-on night vision that did not require re-zero, better optics, and better stock, and it had to be suppressed. The barrel had to be short enough to allow maneuverability yet long enough to deliver a 10” group at 1,000 yards
18" barrels had no problem performing along with 20" barrels. There were XM-3s made but this rifle seems to be only one that is available for non-military ownership.
The package also includes
Scope SN: Q04961; Sniper Data Book with some firing information; PVS22 Night Vision Device SN: 2896D (mounting fastener is broken, seems as though it can be repaired; refer to picture); appears complete tool/cleaning kit with cleaning rod; sling; suppressor case and wrap; SUPPRESSOR NOT INCLUDED; bipod; cold bore shot target; instructions; iM3200 Storm case