It won't break, but may get lost, so a spare safety spring and plunger for the B-M is a good idea. (This is the plunger and spring that go inside the hammer pin under the safety; they have a habit of popping out when the safety is removed.) Since there is no comparable part on the U.S. Colt type, so you will have to order one specifically for the B-M. Otherwise, 4V50 Gary has it about right.
Jim