Questions Global Search not returning all records

I've been having trouble with the global search not returning all our items that it should.  Here is what I found.

If I search for "AAA" without quotes, it finds all items (stock and non-stock) 

If I search for "AAA-1" without quotes, it does not find any items, even though they exist.

If I search for "AAA-1" WITH quotes, it finds that item and all other items that start with that ID.

If I search for "AAA-2" WITH quotes, it returns all the items that start with AAA, including all the items that start with "AAA-1".  

It's as if the "-1" is being excluded when quotes are used and something unknown when quotes are not used.  I also notice that when I include the quotes, the results show up with the search term partially in bold (AAA-1).  Is this normal behavior?  How do I get more consistent results when a user uses copy/paste with an inventory item?