Learn English – “try” or “try out” (difference?)

Usually when applied to a verb involving speech, out involves the addressing of a group, normally a non-specific group, as in "anyone who will listen."

John spoke out when he saw injustice being done.

Mary shouted out for help.

The bailiff read out the charges against the defendant.

In other words, all who could hear were being addressed in each case.

Don't confuse "read out" with readout, however. As a noun, a readout is simply "a visual record or display of the output from a computer or scientific instrument." [NOAD]

They're of course both grammatical, but there is a conventional meaning difference that may not be obvious, as there often is with a verb like try that takes both Equi infinitive and Equi gerund complements. Such available syntactic bandwidth is likely to get used for pragmatic purposes.

In this case, the gerund is the one without any special entailments — i.e, saying

1. He tried opening the door.

requires no special assumption by a listener — or at least is intended to sound that way — while in

2. He tried to open the door.

the infinitive complement (but not the gerund) is subject to the Gricean interpretation (i.e, an interpretation, predictable from Grice's Maxims), that, if one can only say truthfully
"He tried to open it" instead of just "He opened it", then one conversationally implicates
his failure in opening it.

So, in context, (1) above can continue with any of the following:

• but it failed to open.
• and it creaked loudly as it swung open.
• and found that there was a body in the dining room.
• and the door fell off.

but only the first one is appropriate as a continuation for (2).