Thanks, Brian. Very helpful. Previously I couldn't understand how using a longer screw could prevent grip cracking (as described in the MWO). Shorter shank might help a little.

Obviously the significantly longer threaded portion on the MWO screw would hold better - and help extend the life of grips starting to wobble.

With MWO-W1 being issued the same day as -W2, it would be interesting to see if an otherwise original M1A1icon that had one of these MWOs performed also had the other. (for those who don't remember, MWO-W1 replaced the hammer and hammer spring to reduce trigger pull).