Robert Green wrote:

Last night I was watching a Texas rancher threatening a repo man with
a gun, saying he had the right to shoot anyone coming on his
property. Don't car loan contracts require that the rancher allow an
agent of the bank access to the truck? In the end he backed down,
probably because there was a film crew, but he seemed quite sure of
himself.

I'm in Texas and can confidently report that the rancher was wrong. However,
a civil contract has no bearing on the criminal law. Also note the
following:

Follow along. First a definition:

Texas Penal Code: § 28.03. CRIMINAL MISCHIEF. (a) A person commits an
offense if, without the effective consent of the owner:
(1) he intentionally or knowingly damages or destroys the tangible
property of the owner;
(2) he intentionally or knowingly tampers with the tangible property of
the owner and causes pecuniary loss or substantial inconvenience to the
owner or a third person; or
(3) he intentionally or knowingly makes markings, including inscriptions,
slogans, drawings, or paintings, on the tangible property of the owner.

Now check this out (emphasis added):

Texas Penal Code: § 9.42. DEADLY FORCE TO PROTECT PROPERTY. A person is
justified in using deadly force against another to protect land or tangible,
movable property:
(2) when and to the degree he reasonably believes the deadly force is
immediately necessary:
(A) to prevent the other's imminent commission of arson, burglary,
robbery, aggravated robbery, theft during the nighttime, or CRIMINAL
MISCHIEF during the nighttime; or