Good luck. If you want the exact death date, you might want to order the military service record of
Sims - that record should give his exact death date. If I'm not mistaken, you should be able to get that record in Nashville at the
Tennessee State Library and Archives. There might even be a pension record for his spouse, if married. That would come from
Washington, I believe, and would also give his death date as well as other genealogical info not available in his military service record.
If you get a chance, visit the
McGavock Cemetery - nestled in the
Tennessee countryside, beautiful setting with the plantation home a few yards away. Definitely worth a trip to see the gravesite and surrounding area.