You pop two pins and the upper comes off the lower. Takes about 45 seconds.
The uppers stay zeroed when you change them. The lower or how it mates to the upper (some are sloppy) have zero impact on accuracy. All the Accuwedge does is stop the rattle (buy a RRA lower and you won't have rattle anyway)
You have to be careful what you mount on the front sight block because they get hot. Most people choose to mount accessories on a railed handguard. Most blocks are railed for the attachment of back up/flip up iron sights.
In most cases you will mount a scope on a riser to be comfortable and you'll see right over the front sight base and even a full A2 front sight. My guns don't use risers, but I shoot with my cheekbone slammed into to the stock for a consistent index and make sure the scope's eye relief and focus is perfect at that point. You can also get a 4 railed gas block if you desire for a small cost. Actually, I have an unused one.. make me an offer.
