I've got a MKII, but I think the MKIII field strip is roughly the same. You shouldn't need to bang on it. Make sure the hammer is in the proper position. I think it needs to be in the fired position, but I don't remember and my manual is not handy: Check your manual to be sure. Next, pull the catch-lever out. That should pop out the lower end of the mainspring housing. Pivot it away from the frame and you should be able to pull it straight down. Maybe you need to put a little thumb pressure on the back of bolt, but it should pull right out.
Once you have it apart the fun begins: Putting it back together can be even more interesting, particularly getting the pin/lever on the back of the hammer back in the right recess of the mainspring assembly. Again the hammer has to be in the right position to let the pin pivot freely, the bolt stop pin inserted inserted and the mainspring assembly partially pivoted into place, then the gun rotated is backwards (muzzle up) to drop the hammer pin into the right recess.
Good luck.