What is a good way to typeset dot-separated acronyms?

Consider the following plain TeX file.

\tracingonline2
\showboxbreadth20

\setbox0\hbox{CATAPULT}\showbox0

\setbox0\hbox{C.A.T.A.P.U.L.T.}\showbox0

\bye

It produces the following log

> \box0=
\hbox(6.83331+0.0)x54.72229
.\tenrm C
.\tenrm A
.\kern-0.83334
.\tenrm T
.\kern-0.83334
.\tenrm A
.\tenrm P
.\tenrm U
.\tenrm L
.\kern-0.83334
.\tenrm T

! OK.
l.5 \setbox0\hbox{CATAPULT}\showbox0

? 
> \box0=
\hbox(6.83331+0.0)x78.61127
.\tenrm C
.\tenrm .
.\tenrm A
.\tenrm .
.\tenrm T
.\tenrm .
.\tenrm A
.\tenrm .
.\tenrm P
.\kern-0.83334
.\tenrm .
.\tenrm U
.\tenrm .
.\tenrm L
.\tenrm .
.\tenrm T
.\tenrm .

! OK.
l.7 \setbox0\hbox{C.A.T.A.P.U.L.T.}\showbox0

Which shows that without the dots, the font supplies some negative spacing to account for the visual mis-match in ATA However with the dots not only do you not get that, the font supplies a kern to pull the . closer to the P which in this case exaggerates the differences. I think you need to add \kern-0.01em between the letters for whatever values you judge by eye to look better,

You can use the command \textsc to let LaTeX make kerning.

\documentclass{article}

\begin{document}
\noindent
\begin{table}
\begin{tabular}{rl}
\verb|\textsc{C.A.T.A.P.U.L.T.}| &\textsc{C.A.T.A.P.U.L.T.} \\
\verb|C.A.T.A.P.U.L.T.|          &C.A.T.A.P.U.L.T.\\
\verb|\textsc{c.a.t.a.p.u.l.t.}| &\textsc{c.a.t.a.p.u.l.t.}\\
\end{tabular}
\end{table}

\end{document}