So I just got done assembling most of the lower on my first ar build. I was testing out the trigger, hammer and sear to make sure everything was functioning correctly but noticed that as I'm squeezing the trigger back while the hammer is engaged if feels gritty. Now I'm a machinist by trade (not a machine operator) and know that no matter how good the finish looks there are always going to be some mill marks. Just wondering if this is normal. Incase it matters any it is a daniel defense lpk in a psa lower. Thanks for your help.