I sometimes have issues cycling the bolt on my FX Impact M3. It may go smooth or I may have to jiggle the bolt handle or magazine to get it to cycle close. It seems that the probe is hanging up on the mag port when trying to close the bolt.
After some looking online I've seen this has been an issue with the 25cal due to the chamfered edge on the probe. FX has since come out with an updated pellet probe with a chamfered edge with less angle.
Get the K&L probe carrier and take away the concern of the probe flopping loosely due to the retaining grub screw getting loose. Heed my advice, as it’s only a matter of time when that tiny grub screw will end up with a rounded off socket head that you’ll never be able to remove or tighten