According to his WWI Draft Registration Card filed June 5th 1917 in Cotton County Oklahoma his middle name is Hamilton:
Blount Hamilton Howle age 29, b. July 3rd 1889, natural born in Elmore County, Alabama. Living in Walters County OK and farming for self, single, no prior military service, no depandants, Tall, Slender, eyes Gray, hair Dark, no bald, no disabilities. Signed as Blount Hamilton Howle Jr.
The family is in 1920 OK Cotton County, Walters census as Howel.
1900 AL Tallapoosa County Dadeville twsp census BH Howle b. July 1880 is living in household of brother James T. Howle with other brs and sister, census page 128A enumerated by B H Howle. Father Blunt Howle with second wife Emma married 5 yrs and son Carelton is on page 146A enumeraterd by James T Howle.
Have you tried the NARA www.archives.gov or the OK State Archives for their WWI Veteran memories? Cotton County? According to SSDI he had SSN issed in MS in 1963 and died in Washington D.C. so I would check with Veteran's organizations in those places.