along the way in your reloading 'career',many things will pop up that fly in the face of what 'the bood ' says.That is the beauty of being able to come on a forum such as this one and get it all sorted out.
you will buy brand new factory pistol/revovoler brass that is nowhere near minimum case length shown in 'the book'.
you will find brand new brass hat allows the bullet to just about fall into it if you don't size it 1st.
you will find that when you chronograph your loads they are nowhee near what 'the book ' says they will be.
etc,etc. we never stop learning,at least I haven't in over 15 years of reloading
with re: to no. 3.. .450 45colt bullets will just about fall right thru most any 45colt or acp barrel,those are just not right for those 2 rounds.