I am unsure of all the specifics so I can only offer what worked for me.
What you're looking for is in the New Vegas Square. You need to find a man named Jules. You need to pass a "guns" and a "survival" check to learn the recipe. Both are around 60 I believe.
After you speak with Jules you can make .44 SWC ( Semi-Wad Cutters) ammunition. If it isn't showing up for you at a reloading bench you may not be high enough repair or survival skill.
If you use the .44 you would definitely want this recipe as you can breakdown the .44 regular ammo and make the SWC for just a couple more lead and powder with increased stopping power.
This seems to be correct, however it is likely you also need the Hand Loader perk in addition to this. It should appear in your list without high enough repair, so this is not the reason why it does not show up.
Ugh, now I gotta get my survival up to 50 (and the last 10 with a magazine). I have been using my weak old .357 because the .44 didnt have a hand load