So if it has been covered, excuse me. The answer(s) to your question are....
1- Product Liability Insurance. It's expensive.
2- Explosive Licenses for the components used.
3- Time and Expense to test the product for consistancy and develop Loading Data for using your brand of primer.
4- There is plenty more to consider for starting up a new manufacturing enterprise; machinery, tooling, employees, etc. NOT easy to do and takes time. By then maybe there will be no market for your product.
A good example is the AR-15 market. For 8 months they were hard to get and when we got one it sold. Now we have 6 in stock and when I check the store email daily ALL of our distributors are telling me how many they have and offering special pricing to take them off their hands. The fire has gone out on that market.
FWIW,
Emri