Do Osprey Defense piston systems reduce accuracy or increase recoil in any way?

Answer 1

Assuming you're referring to a gas piston system for an AR-15 upper... GPUs and DI uppers both use a gas block... the area of that gas block which makes contact with the barrel will have an effect on barrel harmonics. Same thing with any other object making contact with or adding stress to the barrel. The less harmonic interference you have, generally, the better accuracy you can expect (in conjunction with other things, such as ammo quality, and whether or not you can actually shoot).

IIRC, the differences between the gas block used by Osprey and other manufacturers - both for GPUs and DI uppers - is so negligible as to not be a factor. So you shouldn't worry about accuracy.

Gas piston uppers do tend to have slightly more recoil than DI uppers - much of this is attributed to the extra weight of the gas piston in motion, and also that many GPUs use a long stroke system rather than the short stroke system (as used by the DI system). The difference is mild... very mild.

The real issue to worry about with a GPU isn't either of those two things - it's carrier tilt.