Hw100 FAC springs and lineage

[series2a]

I tried an FAC spring in my Hw100 a while back and found it doing a popping sound when fired, Used it and forgot I’d put it in till a couple of days ago, Blowing Air from the Hammer area as it opened the valve, Also found the cocking linkage was slightly bent.Changed the Hammer spring back and got a new linkage.
Treated it to a new probe and seal as it is now 8 years old.
Feels like a new gun again. Btw I fitted a Power Adjuster 12months after I bought it as it crept over the limit
Would advise all owners to keep an eye on the power levels if std Hammer is still fitted.