Check this out: appears there is an after-market recoil assembly available with a stainless steel rod that's advertised as a "recoil reducer" for the P99. I just ordered one, so I don't know anything more about it.
I am sure that the polymer guide rod will perform as it should. I do not expect any performance gain with a metal guide rod (despite the fact that is is indeed stronger.)
I simply don't like the flimsy guide rod. It shouldn't bend in my mind. It feels chincy. No other good reason.
On a related note, the fact that I like the polymer frame is unrelated to most other parts of the handgun. Despite the fact that I purchaced a polymer framed handgun, I wouldn't appreciate a polymer firing pin either.
I understand what you are saying and I agree with you. I now have full confidence that my weapon was designed and tested to function properly as is. But the bendable guide rod did raise some concerns the first time I took the pistol apart and put it back together. "If I can bend it with my fingers, what will weapon recoil do to it over time?" type questions. But as I learned more, I gained faith in it.
Similar story with my RRA M4. Every time you shoot it, the recoil spring (in the stock) goies 'sproinnnnggg!' as the weapon cycles. Sounds super cheap, but it works and works well.
My 2c - if the polymer guide rod ever fails, then maybe it would be worth spending the $70 for a metal replacement. I don't think its worth $70 just to swap out a perfectly good polymer guide rod though.
I bought the Sprinco about 6 months ago. Sorry to inform that the recoil wasn't reduced in a noticeable way. Moreover the reducer proved to be too long (designed for the .40 with longer slide) and the 'bulb' at the end (front) of the reducer tended to slam against the rim of the passage hole in front of the slide, when returning into battery, thus leaving marks on the slide (no damage yet). After one shooting session the recoil guide rod looked as being run over by a truck, so I kicked it out of my gun and went back to the original plastic rod. My conclusion : not worth the money
I dismantled the whole thing and was able to make a new all steel recoil spring guide by using the Sprinco springs and spring cup, and making a new guide rod (steel) and washers. I hope to have this tested next month with some +P ammo (which was the primary reason for which I bought this thing in the first place).
I don't think the recoil spring is bending when the slide is put back onto the frame. If you notice, the spring fits into a support in the frame. Thus I don't think that it is bending as much as it is when the slide is off the frame. Also, the weakest point of the guide rod, where the two pieces of the rod are connected together, is in this support part of the frame. And upon closer inspection one will see that this joint between the two pieces is actually kind of loose, thus I believe the engineers purposely designed it to flex a little. Why? Perhaps to move with the tilting up of the barrel when the slide is retracted.