Yes the chamber is in the upper, but the recoil system is in the lower and there's a lot of stress that gets put towards the buttstock during recoil with a more powerful load like .223/5.56 there have been numerous polymer lowers snap just behind the rear takedown pin due to it.
Yes i would trust a glock in 10mm. That's a totally different mechanism and its a proven design with a polymer frame.
Yes i would trust a glock in 10mm. That's a totally different mechanism and its a proven design with a polymer frame.