The m19 is not the 'classic' scope normally associated with the trooper blasters, thats a M38. The biggest differences being, the M38 is longer, and the does not have the side illumination socket, like the M19.
Here is a shot of one of my PVC blasters I made using the resin M38 castings. These were for the props used in my fan film:
It is cast off my original.
Note the M38 barrel length, and the fact that there is not much taper, unlike the M19.
BTW, I have not see a tutorial for the M38, but adapting the M19 version should be easy, and the M38 would be actually easier, since there is less taper.
Just to inform, for Star Wars Man's sake: The M19 was used on E-11's in both ANH and ESB, but it is likely that more blasters in ANH had the M38. I don't know of any use of the M38 in ESB. Which scope is the most 'classic' is a matter of personal opinion.
Check out the E-11 ANH Variation Guide on Parts of Star Wars for a list of the known variations in ANH. There may still have been some variations that have not been seen yet. Many blasters were made from real parts in ANH. In ESB most blasters were "stunts" cast in resin, all carrying the M19.