On Thu, 10 Mar 2016 11:46:01 -0500, John H.
wrote:

you are into rapid fire events, that weight will help you with faster
follow up shots.

You've obviously never walked dozens of miles a day carrying a rifle and a pistol
(for the feral attack-creatures). In those conditions, every gram counts.
--

I don't think that is what we are talking about. Harry is charitably
called a target shooter and those water bottles are not likely to do a
lot of sneak attacks. If he is lugging around a silencer, weight is
not that important to him