I already have one and people suggest to take it to a gunsmith and they can fix a few things to make it work better with other ammunition.
I purchased a Sig 9mm P series single stack which had seen light duty as a cop gun in Europe. The trigger on DA was so bad that first shots at ten yards in quick draw would miss a man-sized target! I replaced the spring to fourteen pounds then had to go to sixteen to get consistent primer strikes.
Euro ammo tends to have harder primers than American manufacture. With a rim fire like the Mosquito, going below a certain strike poundage causes more problems than it fixes. When ordering the springs, specify the make and model and you will see a range of spring tensions. NEVER go to the softest unless you're working on a bolt gun.
To replace the hammer spring is really quite simple on a Sig. Take the grips off, then cock the hammer (of an empty gun of course) and notice the little hole in the strut around which the spring is mounted. Put a straightened paper clip into the hole and decock the hammer. The strut will be loose then. To put the new spring on the strut, use a clamp to hold the strut while you slide the spring on and compress it enough to get the paper clip back into the hole, then set it in place and cock the hammer then remove the paper clip. Easy fix for heavy hammer springs.