Monstrum Ruger American Rifles Rimfire Picatinny Optic Rail

Compatibility Guide: The rail is compatible with Ruger American rimfire models ONLY. These include the following cartridge chambers: 22 LR22 WMR17 HMR  You can further verify whether your rifle is rimfire by measuring the distance between the screws on your receiver. If the distance between screws is 2.5 inches, then your rifle is a rimfire version and will compatible with this optic rail. Not compatible with:Short Action or Long Action Ruger American Rifles chambers such as: 223 Remington, 243 Winchester, 308 Winchester, 6.5 Creedmoor, 6.5 Grendel, 6.5 PRC, 6 mm Creedmoor, 7 mm Remington Mag, 7 mm-08 Remington, 204 Ruger, 5.56 NATO, 7.62x39, 300 AAC Blackout, 350 Legend, 450 Bushmaster, 270 Winchester, 300 Win Mag, 30-06 Springfield, 25-06 Remington If the distance between screws is 3.0 inches, then your rifle is short action and will NOT be compatible with this optic rail. You can find that version by clicking here. If the distance be