Crafting ammunition using the Gunsmithing feat always requires a minimum of one day of work:
Crafting bullets, black powder, or cartridges takes 1 day of work for every 1,000 gp of ammunition (minimum 1 day).
1,000 gp gets me 1,000 bullets. However sometimes I just want to craft 20 bullets because that's all I need.
Can I craft less than 1000 bullets in a day with Gunsmithing? And is there any option at all for spending less than a whole day to do it, so that I can craft those 20 bullets in just an hour or something?