Small Correction,my 141 8x57IRS is a RIMMED cartridge and came with the rear mount base for a pivot mount. I bought the remainder of the mount from MAK and installed it in about 15 minutes and am very pleased with it. Mount cost a little over $500 and is really nice. I have only seen 2 of the 141's as that's all my dealer recieved but both had the rear base and the front dovetail where the pivot mounts was filled with a blank.