HBP various responses and thoughts

[Jim Ferer]

Pippin: " No, he didn't. The more you read his confession the more
gaps  and suspicious areas it has. He mouths like he's been hit with a
 silencing spell at one point, (and now we know there's nonverbal, 
wandless magic), no one ever explains why he needed to kill all  those
Muggles"

Amy: "He didn't. He just needed to create a big enough explosion that
it would be plausible that there was no body, and enough chaos that no
one would notice a running rat. Or wolf, as the case may be."

Agreed. Peter didn't care if none or a hundred Muggles were killed -
he just wanted to escape.

Amy: "no one ever explains *how* he did it -- if Voldemort  knew a
spell that would kill everyone within twenty feet of himself,  don't
you think he'd use it to perpetrate a few mass Muggle killings  now
he's back?"

The key is that what Peter did was probably improvised, at least in
part. Either Peter somehow let it be known where he would be found,
sure that Sirius would come after him, or got caught by surprise. Even
if Peter planned on Sirius finding him (not likely unless Peter was
under orders from LV) there's almost no way Peter could know exactly
when, where and how Sirius would confront him.  It's also possible the
size of the explosion surprised even Peter - he might have cast a
Reducto on an actual gas line without knowing it was there.

I guess my point is that things like the Peter/Sirius confrontation
can't be planned out in every detail.  There's too many uncertainties.
Peter got lucky.

Jim F.