I own a 535 combo and don't have a problem with the trigger personally.. Love how it points and generally handles over the 870, I can hit most of what I shoot at with this budget shotgun. BUT...
What BIGREDD says about barrel/reciever fit is right on, poor quality inspection or cost savings to bring this bargain price.
For me- I don't use a shotgun much until the fall, and then simply put, I use it to kill game.
Does not have to be pretty, or the best quality but this Mossberg does way outperform my old (bought new) Rem 870 supermag POS.
Also look at Stoeger pump.. Heard great reviews.