So one of my players was wondering if it would possible for him to research advanced firearms in the Emerging Guns setting I'm currently running a game in.
I had a look at the spell research rules and came up with the following, which I'd like some feedback on;
Firearm Research Rules
To design and craft a new firearm, it takes a number of workdays (8 hours) equal to 1.5 × the cost of the firearm ÷ 1,000 gp. This process requires the Gunsmithing feat and a suitable workshop. By adding 5 to the research DC, you may attempt to design and craft a new firearm without a suitable workshop.
Each Day:
Spend 500 gp for research costs and rare ingredients.
Attempt a Craft (Firearms) check* and a Knowledge (Engineering) check* against the research DC of the type of firearm, these checks are done as part of the 8 hours work required. You cannot take 10 on these checks. If both checks succeed, you make 1 day's progress toward completing the firearm. When your days of progress equal the total number of days needed, the firearm is completed and you may craft additional firearms of this type as per the Gunsmithing feat.
If either or both research checks fail by 4 or less, you make no progress. For each check that fails by 5 or more, your research has led to poor results and you lose a day of progress toward completing the spell.
Research DCs organised by gun rarity levels and types of firearm follow:
No Guns
Early N/A
Advanced N/A
Modern N/A
Very Rare
Early 20
Advanced N/A
Modern N/A
Emerging Guns
Early 15
Advanced 20
Modern 25
Commonplace Guns
Early 10
Advanced 15
Modern 20
Guns Everywhere
Early 5
Advanced 10
Modern 15
*As normal, circumstance modifiers may be given to your skill checks by the DM.