I'm not sure about the mb550 but the Bridger 4 coils I had were tough to open I removed 2 springs until the other two start to get weak . They were to hard to open by hand . Bed bed bed your trap solid don't skimp on time and energy here , this is the part that makes it hard work. Look for scat and tracks , intersections of old logging roads , or any intersection of trails, powerline any easy travel route . Yotes use these a lot they travel fast at night