I am continually amazed at the quality of customer service in which pretty much the entire gun industry works at.
Yesterday i emailed bear creek arsenal because after a year of owning a completed upper from them, i realized the split mlok rail that was on it was loose and i could not get it tight. I had a response within 30 minutes and an offer to replace it with the non split lock version as well as telling me they had discontinued the split mlok. Very happy with this, as the week before i had ordered the non split version for a new upper and am very impressed with it.
Their instant chat feature also has people that are actually familiar with their products.
The previous week i emailed midwest industries asking a question about their blast can and got even more information than i had asked for, follow up responses were less than 2 minutes apart.
I cant think of another industry that has this good of customer service.