  This paper serves as an update of the previous work entitled
``Heavy-Flavor-Conserving Hadronic Weak Decays of Charmed and Bottom Baryons".
We make an improvement on the bag wave functions by removing the center-of-mass
motion of the bag. All the baryon matrix elements are now calculated under the
same framework without introducing new parameters. The matrix elements of
4-quark operators are found to be nearly twice larger than the previous ones.
The calculated branching fractions of $ \Xi_c ^0 \to \Lambda_c ^+\pi^-$ and
$\Xi_b^- \to \Lambda^0_b \pi^-$ are both in agreement with current experimental
results. For the yet-to-be-measured heavy-flavor-conserving decays, we find
${\cal B}( \Xi_c ^+ \to \Lambda_c ^+\pi^0) = (13.8 \pm 1.4)\times 10^{-3}$,
${\cal B}( \Xi_b^0 \to \Lambda^0_b \pi^0) = (2.6 \pm 0.3)\times 10^{-3}$,
${\cal B}( \Omega_c ^0 \to \Xi_c^+\pi^-) = (2.0 \pm 0.2)\times 10^{-3}$ and
${\cal B}( \Omega_c ^0 \to \Xi_c^0\pi^0)= (1.1 \pm 0.1)\times 10^{-3}$. They
are all accessible to LHCb, Belle and Belle II and can be tested in the near
future.
