I have a Bryco model 59 in 9mm. The model 58 is built on the same frame and the only major difference is the 58 is chambered for .380.
I have put somewhere around 1000 rounds through mine and it has not kaboomed or even threatened to kaboom. I am the third or fourth owner of the gun and so it's impossible to tell how many rounds it has run.
It is picky on the ammo it likes. UMC seems to work best with mine.
Now, to address your question; breakdown is VERY easy.
Remove the magazine and make sure the chamber is empty. Point in safe direction, and dry fire. (yeah, makes me cringe too) Look at back of slide. you will see a "keyhole" shape. (see photo) This is your slide release.
Using a pen or similar item, press the hole in the slide release GENTLY. Lift up on the rear of the slide until the release clears the frame. Be careful here because there is a spring that will shoot itself and the slide release across the room. Turn pistol muzzle up and let the release, spring, and firing pin to fall out. Pull slide slightly rearward and lift. When the slide clears the chamber, it will go forward and come off the frame. Take note of how your slide springs are arranged when they come out of the frame/slide.
Clean your pistol, and reassembly is reverse of breakdown.
GOOD LUCK!!!!