I just emailed BM on the same issue, then decided to check here and found the thread.
When I bought my Varmint Special, I chose from several and picked the one with the best trigger. 1st stage was glassy and 2nd felt just right.
After about 40 rounds, I lost the 2nd stage. It was a cold day. By the time I got home with it and it was warmed up, the 2nd stage was back.
I adjusted it anyway, ended up with a gritty 1st stage.
Then I saw that the installation instructions talked about 1/20th of a turn, I had gone 1/4 turn. I've backed it out a touch at a time, each time I've cleaned it, with no improvement to the 1st stage feel. I did as the installation instructions said (back out until 2nd stage is lost, then clockwise 1/20th of a turn), but still have a gritty and inconsistent 1st stage.
just got their answer: they hadn't heard of cold weather affecting the 2nd stage. No advice other than saying they have the Neco grease for sale.
Since the trigger felt great to begin with, and the only change other than adjustment has been to clean and lubricate with the wrong stuff, the grease is probably going to be the cure.