From the shape of the top jaw of the hammer, it looks like a Patilla "miquelet" pistol. The Patilla "miquelet" lock had an incredibly fascinating and long history, as well as a period of use. The Spanish developed the lock in the late 16th century and it was in use by the early 17th century. This style of lock was developed about the same time in Italy as well, due to interactions with the Spanish, but the Italian version had some stylistic differences. Although it didn't entirely replace matchlocks, the Spanish used this lock from the early 17th century until the late 1740s (in some places into the 1770s), when it was replaced by a more "French-style" lock. The Padilla lock was so rugged and easy to repair, the Spanish re-adopted it in the 1780s and used it until it became obsolete in the 19th century. There were even percussion miquelet locks that were not conversions from the earlier flintlock design that were used until the development of cartridge firearms. These types of weapons were in use in much of what is now the United States in areas that were colonized by the Spanish and saw use during the American Revolution. See the attached images of a Spanish miquelet pistol for comparison to Raphael Adolini's pistol from Predator. This pistol likely dates from the early-mid 18th century.
