As I replied to Robert, I'm registering with this forum because I took delivery of my first R51 yesterday.  While I've not yet put any ammo through it (soon, however), I took the opportunity (four times already !) to disassemble and re-assemble the R51, just to prove to myself that - done properly, it's not the chore many in the firearms community describe it as, and it wasn't.  I'm also interested in whether anyone is aware of after-market, 1) triggers (my only complaint of the R51 design), or 2) grips, preferably grips that are a bit oversized.  I'm further interested in whether anyone has found it necessary to adjust the front/top "lip" of Gen 2 magazines.