The set of springs installed from the factory, after around 500-600 rounds, started cousing FRFB. So I ordered 3 new sets from Kahr online shop.
Last weekend at the range I replaced the old with a new set.

The new inner recoil spring looks longer than the old one, much longer.
I know it's because the new one had not been pressed in yet!

I could not do it by myself alone to squeeze 3 pieces: the guide rod, the outer recoil spring and the inner recoil spring, together into the slide. My fingers had not enough power to resist the springs energy. The long un-pressed in inner recoil spring seems causing most trouble. I had to ask for help from a range staff. We together spent about 15 mins to squeeze them in. Finally we succeeded. But my 2 thumbs and 2 index fingers are still hurt after 3 day past!

For betterment in the next round of spring replacement ...do you guys have any tip to advise? A tip that I can do it by myself alone.

I see the sticky thread at the beginning of the 1st page of the forum the tip for easy insert guide rod and springs avoiding the open end of the springs to poke out of the hole at the end of the slide. Having them oriented in either 12 or 6 o clock direction. But they seem already "pressed-in" springs. I want to know how to efficiently deal with a new spring.