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and come to think of it, is the accuracy of the rifle, or any 'take down' rifle affected by the barrel being removed and replaced. It would seem to me that for the performance to remain consistent the torque of attaching the barrel would have to be exactly the same as when it left the factory, IF it leaves the factory in one piece.
The 10/22 takedown has a knob you set once to adjust the barrel/receiver mating. After that it just rotates and clicks into place to where you set it. I imagine the PC9 is the same, but I can't say for sure.
If Ruger supplies different calibers in the future this would be interesting to see.