I got two level 4 armor BP(L)s in about 300 clicks on a level 1 blueprint (caly). This was about a week ago: I don't truly believe you went 5k clicks without a single one... Sorry I just do not.
By equipment do you mean components? I thought you meant equip-able items.
If you do mean components however (which I assume you do, as that is the yellow book), then I did get a level 4 bp recently, though mostly I just get 1-3s, but this is mostly clicking level 1 or 2 bps. The level 4 bp I looted was "Metal Mountings".
I also have a Level VI BP (Solar 12V Gel Batteries), but I am unsure if I looted this or was given it or something a long time ago. I just noticed it now.