You can use either MPN:VDU1-6FFSR1 or MPN:VDU1-6FFSR2. The SR1 is a standard MIL style reticle and can be used with any caliber and the SR2 is a 7.62 reticle which will be caliber specific to 7.62. It can still technically be used with any rifle in any caliber, but it is calibrated for easy use with a rifle in 7.62.