Love this upper riser - TANDEMKROSS Straight Upriser Chassis For Ruger PC Carbine

There was one issue that drove me crazy. There is a gap between the reciever handle and the upriser which made me nuts. The fix is to back off the buffer tube some after screwing it all the way in. You might have to adjust the upper reciever screws as well to get it right. Make sure you tighten them evenly, starting with the rear screw first.