The following is the OST list of "Arms Factory". Basically these songs cannot be found online. The part at the beginning of the video you mentioned (driving across the railroad) should be song 7: "Mississipi Delta."

Turn Around by Extreme Music ?

2. Oh Freedom by Big Score Music?

3. The washington post by A.s. Philhaemonic Schiberr ?

4. Baseball Crowd Organ 01 by Sound Rangers ?

5. Battle hymn of Republic by Big Score music ?

6. Poverty, CA by Benjamin Daniel Zarai ?

7. Mississippi Delta by Littlewood and D. Hunt ?