Boji, First, congratulations on having the H&K. I have one as well. My experience with it is just a bit different than yours in that I find the squeeze cocker very easy to use. Once squeezed it requires (for me) no more thought than one would give to the grip safety on a 1911.
I wonder if applying a little oil might lighten the effort for you. The first time I fired my gun I was gripping excessively hard. Quickly learned that it took very little pressure to use, no more force than any standard grip.
Of course the cocker, besides cocking the gun, serves as a safety, and a slide release. Because of its gas operation, if the extractor should break (highly unlikely) the weapon would still eject cases and could continue in operation.
The H&K is almost ridiculously accurate. I actually laughed out loud my first day at the range because it was performing way above my abilities. Those holes in the target just kept landing on top of each other. I couldn't believe what was happening. Never happened for me with any other gun.
Its a marvelous gun. A few agencies used it, but it was always expensive, too expensive to produce today.