HOW TO... Adjust
velocity on the FX Crown.
There's a lot of us that like to shoot the .25 cal MKII's at speeds that are in the 830's, 850's, 870's, 890's (shooters preference). The new Crown's are coming out of the factory shooting the MKII's at about 800's - 810's. So, how do we increase the velocity?
An owner
might think that by simply taking out the slack from this sliding block (behind the power wheel) they'll increase the velocity to it's maximum potential. This is easily done by removing the power wheel and screwing in the setscrew that touches the cam on the back of the power wheel. Seen here...
True and not true, it depends on how far you want to go. Ultimately, it's a balancing act.
If you only adjust the setscrew, you'll initially gain velocity but as you adjust it further you'll start to lose velocity. If you adjust the regulator at this point, you'll start to gain velocity again.
While I admit that I don't have all the details on what specifically happens internally, I do have a theory...
The hammer hits the valve harder and harder as you adjust the setscrew. At some point, it hits so hard that it starts bouncing back and closing faster. By increasing the regulator pressure, you increase the resistance behind the valve. Since there's more resistance, the valve stops bouncing back. Since there's more air pressure, more air is able to escape and your velocity increases.
If you continue to increase your reg pressure, you'll end up putting too much back pressure on the valve and your velocity will start to drop again.
So, in my opinion, the best way to get more velocity out of the FX Crown would be to slowly increase both. A few turns on the setscrew, then a few bar on the reg. Then back to the setscrew. Then back to the reg. Think of it as if you were "sneaking up" on the fps you're after.
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