  The nature of Type Ia supernovae remains controversial. The youngest remnants
of Ia supernovae hold clues to the explosion and to the immediate surroundings.
We present a third epoch of Chandra observations of the $\sim600$-year-old Type
Ia remnant 0519-69.0 in the Large Magellanic Cloud, extending the time baseline
to 21 years from the initial 2000 observations. We find rapid expansion of
X-ray emitting material, with an average velocity of 4760 km s$^{-1}$. At the
distance of the LMC this corresponds to an undecelerated age of 750 years, with
the true age somewhat smaller. We also find that the bright ring of emission
has expanded by 1.3\%, corresponding to a velocity of 1900 km s$^{-1}$ and an
undecelerated age of 1600 years. The high velocity of the peripheral X-rays,
contrasted with the modest expansion of the main X-ray shell, provides further
evidence for a massive shell of circumstellar material.
