George, Good job is describing your ancestor. I'll offer you some minor points as I see them.
"Pittman James A. - entered service Aug 10, 1861 Columbia, MS. CSA Co F, "Marions Men" 7th Miss. Inf. Regt - Camp Clark, Handcock Co. Bay St. Louis. Miss."
Entered service in Columbus, Mississippi (Located in Lowndes County) Camp Clark was in Hancock County, Mississippi.
The following is the NPS information on this unit and I've added a little to the information in the Camp Chase biographies. This soldier was also with Company I of the 3rd Mississippi Infantry and is buried at Camp Chase.
According to the Soldiers and Sailors Database by the National Park Service Private William P. Marshall served in Company I of the 3rd Mississippi Infantry and noted an overview and the compiler has corrected mistakes and or additional information made with brackets.
“3rd Infantry Regiment, organized in the spring of 1861 at Enterprise, Mississippi, contained men from Hancock, Newton, Hines, Yazoo, Harrison, Copiah, Jackson, and Sunflower counties. After serving in Biloxi, the unit was assigned to General L. Hebert's and Featherston's Brigade, Department of Mississippi and East Louisiana, and was active in various conflicts around Vicksburg. It continued to serve under General Featherston in the Atlanta Campaign and in Tennessee and North Carolina. This regiment totalled [totaled] 572 men in February, 1863, reported 88 casualties at Peach Tree Creek, lost many at Franklin, and had only 71 present for duty in December, 1864. It surrendered with the Army of Tennessee. The field officers were Colonels John B. Deason [Find A Grave Memorial # 54567846] and Thomas A. Mellon; [Thomas Armour Mellon – Find A Grave Memorial # 20848566] Lieutenant Colonels Samuel M. Dyer, [Samuel Morton Dyer – Find A Grave Memorial # 112226925] Robert Eager, [Find A Grave Memorial # 35642371] James B. McRae,[Believed to have birthdates 1827-1906 and probably buried in Wayne County, Mississippi] and E. A. Peyton; [Elijah A. Peyton – Find A Grave Memorial # 5990257] and Major William H. Morgan.”
A card from the U.S.A., General Hospital, Nashville, Tenn shows that James was admitted Feb. 10, 1865 with a simple fl. Rt thigh (slg (?).
There is a place on this card for listing missile, it is filled in Can. Ball
It does say Con. Ball not Can. Ball
From my experience the doctors listed the part of the thigh that had been wounded. I could be incorrect but it looks like 1st and not slg. In other words Right upper thigh.
"Feb 17, 1865 he is shown being to Champ Chase, Ohio. He was received at Camp Chase Feb. 18, 1865. This is one of the most notorious Union Prisons of the war."
From my experience he was either in Prison Number 2 or Number 3 at Camp Chase.
The majority of the Union guards at Camp Chase were members of the 88th Ohio Infantry.
He appears to have been wounded and taken prisoner on Christmas Day of 1864 at Pulaski, Tennessee. The following is a rough idea of what may have happened. General Hood put Major General Forrest in command of the retreat of the Army of Tennessee. Hood's wounded had been at a Franklin and Columbia and other Confederate hospitals when he retreated. Some of the wounded were left in Confederate hospitals and taken POW by the Union. Some of Hood's soldiers had also been sent back Southward before the Battle of Nashville. During the retreat from Nashville the last place the Confederate wounded had been left at was Pulaski, Tennessee. I believe this was the same day of the Union occupation of Pulaski. Union General Wilson and his cavalry raced after Hood's Army. They entered Pulaski, Tennessee on December 25, 1864. Forrest on the other hand had a plan for Wilson. Forrest set up an ambush near Anthony Hill, Tennessee just outside of Pulaski and Wilson and his cavalry were cut to pieces and retreated back to Pulaski. Forrest than charged the cavalry under Wilson and now the reverse was true the Confederates were chasing the Yankees. After a few miles Forrest called off the attack and likewise Wilson called off advance upon Hood's Army. This action made another star for General Forrest as he was made a Lieutenant General and saved Hood's Army.
In my opinion the correct Confederate prisoner flow for your ancestor would have been taken POW at Pulaski, Tennessee and then transferred to Nashville, Tennessee where he entered the United States Army Hospital number one and then transferred to the Provost Marshall and then transferred to the Military Prison at Louisville, Kentucky and the forwarded to Camp Chase where as you stated arrived on February 18, 1865.
You have some very small typo errors such as Champ Chase. "Feb 17, 1865 he is shown being to Champ Chase, Ohio. He was received at Camp Chase Feb. 18, 1865. This is one of the most notorious Union Prisons of the war." I don't know of anyone who has not made a typo every now and then.
For more reading about Forrest at Anthony's Hill enter on google Battle of Anthony's Hill.
I was able to add very little.