small parts i have been getting mostly DPMS and del-ton.
one of the last DPMS bulk packs came in a bag marked rock river. don't know if it means anything or not.
LMT makes very good LPK, as does rock river i'm told and daniel defense. my last DPMS lower parts kits seem to be just as good as the LMT's and colts i have had so i am not in any hurry to spend more on them.
i got some bulk LPKs from sarco a few years ago. they had a lot of colt parts in them at that time. don't know what their shipping now. so not all bulk stuff is bad.
what i do is assemble the lower and see if everything works as it should. see if the trigger is not too rough and too hard on the pull.
i have only had one that had a hard trigger lately it was in a cmmg kit. what i did was swap in an old colt small pin hammer and the trigger lightened right up.
strangely the cmmg hammer worked fine with another trigger --
my advice is just get the DPMS LPK if you want a standard trigger. if you want a two stage or adjustable that is another matter.