I recently acquired a S&W 686-2 but don't know too much about it and I've got a few questions that I hope are simple enough to answer. What does the "-2" mean after the 686, I couldn't find much detail online surprisingly? I can't tell how long the barrel is, I measured from the cylinder to the end of the barrel, its just under 6", but from the "housing" (not sure of terminology - where the barrel meets the "gun") to the end of the barrel its exactly 5". I've been told this gun will fire both .357 magnum rounds and .38 special rounds, correct? What is a good practice round I can buy for the range while I learn to shoot this gun? What is a good round for actual self defense? Thanks in advance from someone who is excited to start learning.