HI there!
big fan of the super-safety though fairly new to it. I have a total of 4 steel sets from 2 different vendors and am running them in an AR9, 2x AR15s, and an MP5 clone. I've used a jig to cut my own triggers and have been getting super safe for about a month, but have lots o' time on my hands and so have put them through the paces. All 4 worked really well until a few days ago when I started having this same problem....... being a newbie, please excuse me if this question seems kind of backward: As I look at the hammer and lever, it seems to me that sanding down the lever where it contacts the hammer to fix this situation could also be done by sanding down the corner of the hammer where it contacts the lever.... there is a lot more material on the hammer and so I am wondering if this is a better solution because the lever is made of less mass and so may wear out quicker.... please correct me if this is incorrect logic.
With regards to the trigger tail being too rounded off, in an effort to fix my problem with one SS I installed a new hammer that is just ever-so-barely rounded. This did not help the issue at all.
If the take home message (thanks Hoffman!!) is that the lever is causing premature unlocking of the trigger, well this info is gold and I am super happy to find out the reason after several days of searching.
cheers!