45.R.M.G.71. would indicate Imperial Army use not police;
the Machine Gun Company of the 45 Regiment, weapon number 71.
Later on regiments added additional machine gun companies, and would add the company(kompany) number
and it would look something like 45.R. 4.K. xxx. - with xxx for the weapon number using 1 to three digits.
Low numbers, unless they are like single digits or some other number a specific person chases afd no more scarce, nor worth more than a high number, like 10,000!
Welcome to the board- and there is much more info here- you just have to read!