There's a fair amount of good information on this site regarding bolt gun and AR platform actions/receivers, but I can't find much addressing options for M1As. I've read that most stock NM/UM SAI M1As out-of-the-box just about as good as the M1A platform gets, but what are the reasons for going custom? What are the receiver options? I've read of the SEI debacle going on now, hear the LRBs are well worth the wait, and the Fulton Armory ones are regarded as being lower quality, but readily available. Do SAI's get overhauled/built on by gunsmiths like 700 actions are, or are they just left alone? Who are the good M1A gunsmiths? If there is no list, can we get one started here? What are the general run of services done to them, and what things need to be considered before starting down the road to a custom M1A?