It's a MKIII. Notice the mag release button and key-lock hole on the safety.
Are you trying to disassemble?
If so, you need to pull the trigger first. There's a magazine disconnect "safety" so you'll need to insert the magazine in order to drop the hammer. Push the spring bar forward with your fingers to give it a little pressure and then pull the trigger in order to drop the hammer.
The spring bar will then swing all the way out. Give it a quick yank towards the bottom of the frame and the pin will pop out.
Point the barrel upwards and pull the bolt backwards. This will reset the hammer and the bolt will slide out the back.
Push the grip frame BACK along the barrel. (barrel pulls off the front) There is an L-shaped locking piece up from the front of the frame that holds the barrel in. This may take some force. If needed, tap on the back of the barrel snub with a wooden or plastic mallet.
You're disassembled at this point, clean what you need to and lube the trigger components if necessary.
To go back together, the order is reversed but not quite the same.
Push the barrel back onto the frame as normal. Now, before you put the bolt in, use the pin of the spring bar to make sure the locking hole between frame and barrel are lined up. Just push it through (from the top is fine) and it will line them up. Then, make sure the hammer is down all the way (push with finger) and make sure the mainspring on top of the bolt is centered. There's a little yoke at the back end that can cause the pin to hang up if it's not centered.
Slide the bolt in and then, using a screwdriver, apply pressure to the bottom of the hammer (looking through the frame). Pull the trigger to drop the hammer forward.
Point the gun down. Slide in the spring bar pin. This may take a tap with the heel of your hand to fully seat the pin. Let the bar fall forward as far as it likes to.
Point the gun UP. There's a push rod attached to the hammer that you need to line up with the center of the spring bar before they'll go together. It can get caught on two of the many crossrods through the frame. There's no way to explain this other than to say "keep trying."
When the spring pack seats almost fully but needs about 10lb of force to push home, you've got it. Lock the bar in place.
Good luck.