Beamer: itemize indentation with respect to the previous

Question

I have already tried searching (here for example) but I have not found a solution to my problem. When in beamer I use an itemize environment inside another, at the moment what I get is this:

I would like to move the the second "block" of items to the left. (The same considering the third with respect to the second, the fourth with respect to the third...). This picture explains better what I mean:

(Note that I would like this behavior in all slides). Embedding in the preamble

\usepackage{enumitem}
\setlist{leftmargin=3.7mm}

solves the problem but I would not like to use enumitem because, as explained here, it could disturb beamer.

\documentclass[14pt,handout,t]{beamer}
\usepackage[english,italian]{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\geometry{paperwidth=297mm,paperheight=210mm}
\setbeamersize{text margin left=100pt,text margin right=100pt}
\usepackage{pifont}
%\usepackage{enumitem}
%\setlist{leftmargin=3.7mm}


\begin{document}
\begin{frame}
      \begin{itemize}
        \item[\ding{226}] Miglioramenti su SFC e rumore possibili attraverso:
          \begin{itemize}
            \item[\ding{229}] riduzione peso fan e LPT
            \item[\ding{229}] riduzione peso e drag nacelle
            \item[\ding{229}] aumento efficienza fan e LTP
          \end{itemize}
      \end{itemize}
\end{frame}
\end{document}

Answer 1

You have to set the lengths \leftmarginXXX:

\setlength{\leftmargini}{3.7mm}
\setlength{\leftmarginii}{3.7mm}
\setlength{\leftmarginiii}{3.7mm}