The researcher at this link provides information on these four brothers.
http://worldconnect.rootsweb.com/cgi-bin/igm.cgi?op=GET&db=lorilynnshouse&id=I216

Individual military service and pension records are available from this site by clicking on the banner at the top of this page.

A capsule history of this unit can be found at this link.
http://mississippiscv.org/MS_Units/1st_Regt_MS_Partisan_Rangers.htm

Also see the 7th. Cavalry website at this link.
http://community-2.webtv.net/Larry812/SeventhRegiment0/index.html