I followed instructions on your site but it did not work. Maybe it is not a Mod 300. All it says on frame is Sterling .25 Auto
I am not sure how many different models Sterling makes, but mine sounds like the same thing. It only says Sterling 25 Auto on the slide.
Disassembly is simple.
On the left hand side, near the back, just under the slide you should see a metal button. Push that and a catch will spring out the back about 1/2 inch.
Start to pull the side back gently while pulling up slightly from the back. The slide should start to easily lift up.
Once the slide starts to lift up, let the slide move forward (it will on its own due to a spring), still lifting up slightly.
The parts should seperate. The slide will come off (there will be a firing pin and spring in the slide). Thre will be a spring around the barrel and that is about it.
Putting it back together is a bit more tricky. It is the exact same process, but in reverse. However, the parts don't go back together as smoothly as they come apart. I would recommend removing the firing pin and spring prior to attempting to put the slide back on. Before I knew what I was doing, I broke the firing pin right off trying to reassemble it.
Once you got the barrel and spring back in the slide but before you push the back of the slide all the way down, slide the firing pin back in the groove followed by the spring.
Hope this helps
I always say that if someone shoots me with a .25 and I find out about it, I'm gonna be ᴘιssed! Seriously, they quality of manufacture is cheap and not reliable. The caliber was designed as a gamblers hideaway which could bu used at no more than arms length, and was never reliable even at that distance. I saw a guy shoot himself in the head with one, and live for 12 hours afterwords. More than enough time to take that popgun away from your wife and do whatever he wanted to do. In my humble opinion, a .38 Caliber revolver is the ideal firearm for a lady to use for self defense, when she has little or no firearms experience, but needs something utterly reliable that will stop a bad guy. If I had no other choice, but a .25 or a .22, I'd take the .22 and load it with some hot HP ammo. It will do 3 times the job the .25 will.