Plenty info on the internet, Howa advertise the HACT as being end user adjustable.
Personally don't like the HACT two stage,it's a cheap unit but works. The 'saftey' lever (bent bit of metal) was annoying and I wanted a single stage, traded with a member on here for the older Howa single stage unit, didn't like the fact that the 'saftey' was a three position setup with a long throw and audible detent clicks.
Bit the bullet and bought a Timney unit, which is about the only available aftermarket replacement, and it is just OK. About equivalent with a stock Tikka trigger, only the Rem 700 and clones have access to good aftermarket triggers unless you want to drop the coin on BixNAndy who make Sako and Tikka compatible ball bearing triggers.
Back on topic, guys like
@dodgyknees do fine with the HACT trigger (spring replacement from Gunbloke?) and it's a matter of following some simple instructions to do this.
However, I'm sure a local 'smith' will be happy to take your money to fiddle with the screws a bit and claim it has been 'tuned'...