Don't really get your question.
There is no external safety on the Sigma.
It's like a Glock. Uses the "safe action"
type of system. There is a pivot catch on the
trigger. You have to pull both sections of the
trigger for it to fire.
Also there is a striker pin block internally,
same as the Glock. This prevents the pistol
from firing unless the trigger is actually
pulled. This type of pistol will not fire if
dropped.
So it has the internal pin block, and the
trigger pivot safety, but that is it.
With the Sigma, as with the Glock, if a round
is in the chamber and you pull the trigger, it
is going to fire. Period. Some are not crazy
about the system, but it does give you less to
worry about in a high stress situation.
You just have to keep the bugger picker off the
trigger unless you actually mean to fire.
The Sigma is very much a Glock clone. Sure,
some small differences, but overall they are
very close in design and function.
BTW, Glock is the one that named it the "safe
action" system. S&W doesn't call it that, but
the Sigma uses the same basic system as the
Glock.