With the invention of Smokeless powder, Berengar now had the opportunity to create new weapons, and though these weapons could not be mass produced for many months, the earlier he designed them, and tested them, the better it was.
These were no mere single shot firearms. There were many components that went into a repeating firearm, and each part had to be thoroughly tested in order for the weapon to be deemed serviceable. It wasn't a simple matter of drawing up blueprints and putting them into action like he had done in the past. Weapons like these took time to reach perfection.