Create a macro with a single keybinding in a default register, apply by dot-repeating

quickmacro.vim

" Place file in autoload/quickmacro.vim
" 
" Create mapping in vimrc to start and stop the macro with e.g. M:
"
" nnoremap M :call quickmacro#Record()<cr>
" 
" Apply macro by @m, or if you have repeat.vim, just press .

let s:recording = v:false

function! quickmacro#Record() abort
  if s:recording
    normal! q
    let s:recording = v:false

    silent! call repeat#set(":call quickmacro#Run()\<cr>")
  else
    let s:recording = v:true

    normal! qm
  endif
endfunction

function! quickmacro#Run() abort
  normal! @m
  silent! call repeat#set(":call quickmacro#Run()\<cr>")
endfunction