The first one I opened, and by far the easiest is brass 40mm Taskforce. Got that one down to about 2 seconds, safety pin or real pick

The second I opened is a steel 40mm Taskforce. This one requires a little bit more work than the brass, but I'm getting it.
The third, is a Master No.3 I've only opened this once, because I'm scared to close it again for fear of not being able to get it

The fourth one though I'm having some trouble with. I didn't buy this one, I found it out in my tool box. It's old, and there's no sign of the keys anywhere. The only details are that it's a brass padlock with 'Sears' real big on one side. I've been reading through the posts here, and found one that made me think the pins might be security pins. Here's what's going on. The plug will turn slight when tension is applied to it. If I turn the plug slightly with my wrench, it's impossible to get ANY of the pins down. So I've had to use MINIMAL tension. I can get at most 3 pins to set, and I think the order goes 3-2-1 (1 being the front pin) Sometimes, I have to use a bit of force to get a pin down, and when it finally clicks, one of the pins that was already set, re-sets. Anyone have any ideas, other than trying even less torque?