I know that magpul says to use the screw that comes with the LPK for the grip because it's "thinner" than your average grip... I'm ASSUMING it's why they use a 3/4 inch screw instead of your standard 1 or 1.125 inch screw that is mil spec. Well, The one I have was INSANELY dipped in loctite (I hate that damn yellow stuff they slop on the MOE screws, one of the reasons I have spares is so I don't have to use the loctited scres) so I was heating it up with a lighter to get some off when the screw slipped out and vanished in my garage. Now I have some spare grips screws I always get from Ace as backups so I tossed one of those in with a standard gator lock washer (1 inch screw). I looked in the receiver and the bolt with washer doesn't stick out at ALL from the grip screw hole into the inners of the receiver, so no issues with messing of the firing control. I mentioned having to do this one one of the armorers at my precinct and he said that Magpul says specifically NOT to use a lock washer in any of their builds but he couldn't say WHY.... my question is. Is there something in there that will be messed up if you use a star washer in the MOE SL grip I got? chew up the plastic or something? The bolt isn't sticking into the lower receiver with a 1 inch length and an internal toothed star washer on there, so I'm sure it's not damaging the fire control group.
I have NO idea why they only included a 3/4 inch screw in the LPK as the MOE SL is the same thickness between the bolt head and the reciever as an A2 grip... a 1 inch screw still leaves a lot of threads to go through before dipping into the fire control area. It's not like the moe regular grip where the 1 inch bolt ALMOST goes into the receiver interior (even without a washer my grip screw doesn't penetrate into the FC area with a 1 inch screw, but I could see why they would use a 3/4 for the MOE, the MOE SL on the other hand doesn't come close with a 1 inch)....
I'm assuming the no washer is because of that gawd awful gunk like loctite they put on the threads of their own screws, but since that one is lost I'm just making sure that there's not some structural problem that comes from using the standard bolt and an internal toothed lock wash like on my colts etc.