FWIW, most AR lowers are a loose fit to the upper. Mainly I think this is to ensure parts interchangeability and because a little upper rattle has zero effect on accuracy.
If you DO want a tighter lower to upper fit, try a DLASK or Blue-Line lower. Both are Canadian made and on the tighter side - some people shy away from them because they are NOT loose! lol.
As for the trigger, take a look at Questar's offering of the RRA 2-stage match trigger. I have one in an AR180B and it takes the long crappy factory Armalite pull (same as you have in your lower) down to a crisp 4 lbs with near zero creep. There are better match triggers out there, but not for the price ($159).
If you DO want a tighter lower to upper fit, try a DLASK or Blue-Line lower. Both are Canadian made and on the tighter side - some people shy away from them because they are NOT loose! lol.
As for the trigger, take a look at Questar's offering of the RRA 2-stage match trigger. I have one in an AR180B and it takes the long crappy factory Armalite pull (same as you have in your lower) down to a crisp 4 lbs with near zero creep. There are better match triggers out there, but not for the price ($159).



















































