A struggle to find the facts

The below was published in December of 2011....oh how my depth and understanding has changed since then.

I have been working on my family genealogy for several weeks now.  I have even paid money for sites that I have had great success on.  But I still find myself frustrated by the fact that I can't find a marriage record for my great-grandfather, Arthur Clayton Spragen to his wife, Mary Duncan.  A marriage record in this case would be of great help considering it will give me Arthur's parent's names as well as Mary's parents names.

I have put together what I believe is the family history line up to my great, great, great grandfather in the early 1800's.  However, this line depends on my great grandfather in fact being a man who was born in Kentucky and not Virginia named Arthur Spragens, with an "s" at the end of his last name.  According to my grandfather's birth certificate, it states my great, grandfather was born in Virginia.  However, I can't find a record for an Arthur Spragen born in Virginia in 1886.  I did, however, find a record for a draft for an Arthur Spragen who was married to a Mary Spragen.  In this draft record, it list Arthur Spragen as being born in Kentucky.  This is my piece of hope that my grandfather's birth certificate was wrong and his father was actually born in Kentucky.  If this is true, I am able to put together, with the help of records, a family line with dates and events, which includes Arthur Claytons, father, Napoleon Spragens.  Napoleon Spragens was married to three different women in his lifetime, one of which was my great grandfather's mother, Mahala Ford.  Napoleon's father was Joel Spragens.  All these Spragens were born and raised in Kentucky which is fitting that there are many Spragens in Kentucky today.

The question still remains though, if this is true that my great grandfather was born with the last name Spragens, why did he change his name and die as a Spragen?  What situation occurred that he would want to change his name from that of his father and his ancestors?  It is a question I hope to answer in the near future.