Well, the steel slide riding inside of polymer rails has long been proven in Ruger pistols like the P95, P97 and P345 as well as other brands of pistols. In other words, nothing to be concerned about because the polymer is engineered to be plenty strong enough.
That may be.
I do know that Khar had issues and have since switched to steel.
Heres a few pics
Even had a thread on it here @ the firing line.http://thefiringline.com/forums/show....php?p=5298619
I know the Ruger p95 has a beefier rail and maybe Khar had other issues causing it.
Still yet I would much rather having it ride on steel than plastic rails. Smoother and less can go wrong in my opinion.