Isaac's father, Joseph McReynolds is the one with the Rev. War service:

Joseph McReynolds, b. 5 Oct 1760, Caswell Co., NC; d. 14 Apr 1838, Reeds Valley, Russell, VA. Married to: Rebecca Boren, 11 Apr 1783, Caswell Co., NC (was Orange Co.)

Joseph was drafted at age 16 for Rev. War. He was wounded in the ankle Aug. 1780, at the Battle of Camden, SC, known as "Gates Defeat", and was not heard from until the March following. This wound left him a cripple for life.

More notes on Joseph:
p. 428-9, "Pioneer Recollections of So. West VA" by Elihu Jasper Sutherland, Pub. 1984.
"Joseph McReynolds lived in NC awhile and then moved to Saltville, Washington Co., then to Burke's Garden, Tazewell Co., and finally to Reeds Valley in Russell Co., all in VA. He purchased 100 acres on Copper Ridge - north side- from John Husk and Anne Husk on 18 July 1795. Husk had built a little pole cabin there, but McReynolds built another larger log house, daubed with clay and stones, with puncheon floor and a large fireplace. This house was built in Indian times and it is still standing. We are now in it."
"John Jessee was a close neighbor, having also been his neighbor in Burke's Garden. At that time, all of Reeds Valley was a wilderness and Indians still hunted there. A blockhouse or fort was built in the second hollow above Joseph McReynolds home at this place. He had three children when he settled here. Robert, John and Martha (Mattie.)

1838 Will of Joseph McReynolds, Russell Co., VA, Will Book 5, Page 149, Executed 7 Nov 1838:
In the name of God, Amen.
I Joseph McReynolds of the county of Russell and State of Virginia, knowing the uncertainty of human life and the uncertainty of death, and being of sound mind and disposing memory do make and publish this my last Will and Testament, in the words and figures following, viz:
Item 1st. It is my wish and will that my executors herein after named shall pay all my just and honest debts, and after paying all my debts and funeral expenses I will that the residue of my effects be divided as herein after directed.
2nd. I give and bequeath to my son Isaac, all my real estate in the county of Russell, after my death and the death of my wife Rebecca. Should I die before my wife it is my will that my wife shall have the use and profits of my lands or real estate aforesaid, as a home, and support for her during her life and after her death to pass unincumbered and in absolute fee simple to my son Isaac aforesaid.
3rd. I will that enough of my personal property be sold by my executor and executrix herein after appointed, to pay off and discharge my just debts and the residue if any be equally divided between my children to wit, the children of my son Robert now dead to have one eighth part of my personal property, Susanna, Mattey, Phebe, Rebecca, John, Joseph and Isaac to be tween them equally divided as aforesaid.
4th. I hereby appoint my son Isaac McReynolds and my wife Rebecca, executor and executrix of this my last will and testament, revoking all former or other wills heretofore made, do make and publish this my last Will and Testament. In testimony wereof I hereunto set my hand and affix seal, this 7th day of October, in the year of Christ one thousand eight hundred and thirty.
Joseph (X) McReynolds (seal)
Signed sealed and published
in the presence of:
G. W. Hopkins
David B. Alexander
Virginia, to wit: At a court of quarterly session continued and held for Russell County at the courthouse, on Wednesday the 7th day of November 1838. This writing purporting to be the last Will and Testament of Joseph McReynolds deceased was exhibited in court by Isaac McReynolds executor therein named in order to be proved and recorded, and Joseph McReynolds a son of the deceased, who opposes the proof of said will also appeared whereupon the deposition of David B. Alexander, one of the subscribing witnesses to said writing, taken pursuant to a commission heretofore awarded for that purpose being read, and George W. Hopkins the other subscribing witness, and sundry other witnesses being sworn and examined, and the parties of aforesaid by the counsel witness, and sundry other witnesses being sworn and examined, and the parties of aforesaid by the counsel being fully heard it is the opinion of the court that the said Joseph McReynolds deceased, at the time of making and publishing the said writing was of sound mind and disposing memory and was not under any undue influence in devising his property by said writing. Therefore it is ordered that the said writing be recorded as the last Will and Testament of the said Joseph McReynolds deceased.
And on the motion of the said Isaac McReynolds, who made oath, and together with Harvey Gray and Dale Carter, his securities, entered into and acknowledged a bond in the penalty of $500.00 conditioned as the law directs, certificates is granted him for obtaining probate of the said will in due form.
Teste,
James P. Carrell C.R.C.

Check out the McReynolds website at:
http://home.europa.com/~redshank/