To be honest, I haven't used any of my knives other than the BK2 and that was very limited use. I did, however, check the screws on all 3 of my beckers last night(BK2, BK7, BK9) and ALL of them were "loose". I use the term "loose" because they were certainly not tight but they weren't in danger of falling out either. I tightened them all down pretty good so I don't expect any problems. I guess I honestly wouldn't have paid much attention if I hadn't come across this thread......so thank you for making this thread!
I did notice that I think I could get a lockwasher on my BK7 and BK9 without too much trouble. When I tightened down the screws, there is a decent amount of thread left over. After tightening my BK2, I didn't notice nearly as much thread remaining so perhaps the screws on my BK2 are a bit shorter than the ones used on my BK7 and BK9.
jc