I doubt it will letter as a target, although there is an outside chance.

That rear sight leaf, as someone noted yesterday, is many years too
late for the gun. At least 10 years, maybe 15 years. My guess is
that they were installed in 1948, along with a probably refinish.

One rarely sees a triplelock with a patridge blade, which is another
reason why I think the sights were installed much later.

The only other possibility is that the gun was shipped with the
much-earlier single-screw rear sight leaf, and then updated in 1948
to the most-recent pre-WW2 sight leaf. The earlier rear sight leafs
did not have any locking mechanism, and so could come out of
adjustment during prolonged shooting.

My bet is that it was shipped with an M&P sight configuration.

It would be interesting if the owner would remove the rear sight
leaf, and see if it is numbered to the gun. Even that would not
confirm the original configuration. Only a letter will do that.

Later, Mike Priwer