Yes, you lose one stock position with the G28 tube. The positions are also spaced out differently on the G28 receiver tube. That happens to be one of two positions I need for shooting. One is for prone, one for standing/positional shooting. I have the G28 castle nut on my other MR762 which has a 1-8x Leopold. The G28 castle nut looks cooler, but I don't see it being necessary as the standard one is very strong.Why the original castle nut on the buffer tube? doesn't the g-28 stock use the extended nut. Is there a reason for this?