Unfortunately, Wolff doesn't offer PPQ springs. Another thought would be to see if the recoil spring assemblies of the 45ACP PPQ are the same size as the 40S&W or 9mm assemblies. If so, you might be able to buy a heavier assembly from Walther. If that doesn't work, I had a guy make me an assembly for my Steyr M9 that was having a similar problem which Steyr couldn't fix. He actually used a Glock recoil spring. He might be able to fabricate something.