Is this my John Sloan?

I recently found a record at the National Archives connected to a soldier who died during the Mexican War.  Is this my family in the records?  

This find has been so recent that I haven't had much time to look into it very closely.  There might be an easy answer to this question out there, but it also might involve more in depth research. 

My knowledge of my ancestor, John Sloan is limited.  I believe this is him in the 1880 census in Jefferson Township, Fayette County, Pennsylvania.  The youngest child, Joanna, is supposed to be my great great grandmother, Joanna.  She married John Bronson and lived in Fayette County, Pennsylvania.  Her nickname was supposedly Josie.  

According to the 1880 census record, my John Sloan was born about 1840 in Ireland.  As we all know, census records can be inaccurate, so while this isn't conclusive proof about his age and birthplace, it's a starting point.  

 

I've looked all over for him in the 1860 census but haven't been able to find him.   He's been very difficult to track down overall!

 

Records from the National Archives show a soldier named John Sloan who died in the Mexican War.  While this man would be too old to be my ancestor, the records show that he had a son also named John.  According to those documents John Jr was born in 1838, which matches the age of my ancestor within a couple years.  This family was from Allegheny County, Pennsylvania (the same county as Pittsiburgh).  Allegheny County is directly north of Fayette County, where my John Sloan was living.  

(image below is from his widow's bounty land application)

 

 

John Sr's enlistment record (below) is giving me concern that this might not be the same family.  This shows that John Sr. was born in Allegheny County, Pennsylvania, but John Jr's census page reports that he was born in Ireland.  It doesn't seem likely that the father was born in Pennsyvlania while the son was born in Ireland, but it's possible.  It's also possible that in 1847, an Irish immigrant wouldn't have wanted to be known as being Irish, so he may could have lied about his birthplace.  

 

 

Here's a link to view the full set of documents I found at the National Archives.  Is this my family in these records?  Let me know what you think!