Solid Solenoid, spring is a bit weak but still allows for 8-10 dps (which is completely fine), and if you want to you can replace it.
Easy 8 dps with the stock spring, after adding a second spring at the end of the stroke can hit ~13, which is plenty for me.
I stuck this in a stryfe and the pushing distance was perfect. However, I did have to use a 11.1v 3c Lipo high discharge battery for the solenoid to push darts out of a full magazine.
Side note: this solenoid draws 5+ amps. Make sure to build a circuit that can handle 5 amps and 12 volts (minimum).