Originally Posted by inmylife2415
K, please explain
The spring unquestionably speeds up the forward stroke of the bolt. So the question becomes what does it do for the return stroke? Yes, the air has to fight the spring as it returns - but due to the QEV's and re-cock assist providing so much air to return the bolt at its initial rearward travel, I don't believe it's going to be significant as that air will reduce the effect of the spring slowing the bolt down.
It would be an interesting thing to test, but if I had to guess it'll either not matter or maybe even slow it down. Besides that it'll be rougher on the bolt (especially if you're missing your bolt guide bumper) because there's nothing to slow it down during the return stroke.
tl;dr - springs are conservative, and since you're boosting the return stroke with air from the can I think you're going to see more gains in bolt velocity and reduced bolt stick in the forward stroke than you lose on the return stroke. Remember, bolt stick adds to your dwell and therefore increases cycle times and decreases ROF. I wouldn't run it without a spring.
At any rate, I think the eigenbolt with a spring will be faster than a stock bolt - why do you need to shoot faster than that anyway?