Current situation:
I'm required to cite "normative" documents (read: standards and manuals) separately from articles and books etc. Using biblatex and biber with the numeric style I'm doing that by issuing multiple printbibliography commands like so:
\usepackage[style=numeric,backend=biber,bibencoding=utf8]{biblatex}
%... lots of stuff
\printbibliography[type=standard,title=Standards \& Manuals]
\vskip\baselineskip
\printbibliography[type=manual,heading=none]
\printbibliography[nottype=standard,nottype=manual]
which gives a heading Standards & Manuals, prints a list of manuals, leaves a bit of space then the list of standards and finally, under a new heading Bibliography gives books and articles etc. Thus far everything is fine, enter:
The Problem: I'm using the shorthand field in my database for the standards and manuals which works perfect as far as output within the text is concerned and sets the shorthand as the label in the bibliography and prints the details to the right of it - problem is: my shorthands are considerably longer than the labels generated by the numeric style, but even though they're in three different \printbibliography commands, everything gets indented to the maximum width of the label, making the part for books and articles look quite ridiculous.
The following shows the problem with only two separate \printbibliography (and an obviously exaggeratedly long shorthand):

Now what I would obviously want is for each of the \printbibliography commands to only use the indentation actually necessary to accommodate the largest label appearing within, i.e. rendering the Manuals section as above, but the Bibliography section like follows:

Can anyone help me to achieve this? Or give me some pointer where to look?
The above was produced with the following MWE on an up-to-date TeXLive 2014:
\documentclass[10pt,british]{scrbook}
\usepackage{babel}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage{filecontents}
\begin{filecontents*}{\jobname.bib}
@manual{HowTo,
title = {How to Make the World Go Round},
shorthand = {HowToMakeTheWorlGoRound},
publisher = {The Publisher},
year = {2000}
}
@article{Article,
author = {Author, A. and Buthor, B.},
journal = {Journal Title},
pages = {113--126},
title = {The Article},
volume = {65},
year = {1900}
}
\end{filecontents*}
\usepackage[style=numeric,backend=biber,bibencoding=utf8]{biblatex}
\addbibresource{\jobname.bib}
\usepackage[hidelinks]{hyperref}
\begin{document}
\let\cleardoublepage\relax
\chapter{The Document}
Nothing to see here, but we refer to the \parencite{HowTo} based on a principle discovered by \textcite{Article}.
\printbibliography[type=manual,title=Manuals]
\printbibliography[nottype=manual]
\end{document}

