Some good info in this thread (I've learned summot
Hopefully (as well as re-iterating some of what has already been said) I can add something new.
The Shamal preceded the 100 Series; what you have appears to be a Shamal with a target stock (as others have said).
One of the most significant differences between the Shamal and later 100 series is that the Shamal used a separate air cylinder that screws to the valve body at the rear of the action; while the 100 series uses a single-piece tube to house the striker assy and also act as a reservoir. Dale's photos show the join between the two components on the shamal (below / near the front of the breech block) and also the socket cap bolts that hold the valve gear in place in the 100 series (in a similar location).
The "Olympic" trigger was fitted as standard to the TM and NJR100, and was an option on the SM and XM100. To the best of my knowledge it wasn't around while the Shamal was in production; however apparently they can be retro-fitted.
From the pics I wouldn't like to speculate as to which trigger is fitted to yours; however below is a pic of an Olympic trigger for comparison. The Olympic has a straight ally blade, while the standard unit has a curved brass / plated blade.
They really are fantastic, true-two-stage units; and not at all difficult to adjust IME (although it's worth pulling off the side plate to see how everything works before / during adjustment). Mine is currently set at 80g first stage and 160g 2nd stage weights; and is still perfectly smooth and predictable at this setting
AFAIK the Shamal didn't come from the factory with a reg; however this is probably a good thing as those fitted to the 100 Series were pretty nasty tbh; operating with a set pressure and volume of captive air (as opposed to a spring) to dictate the output pressure; these are a pain to setup and can fluctuate significantly with temperature. My NJR has a Welham reg, thankfully!
Hope you enjoy your new acquisition