That's because manufacturers don't want their guns to discharge accidentally. A few weapons have a screw for adjusting spring pressure on the sear mechanism, but others require a gunsmith to polish the mating components to lower sear engagement. (The sear is the catch that holds the hammer of a gunlock at a cocked or half-cocked position.)
Unfortunately, any changes to factory-built triggers can make weapons unsafe and usually voids factory warranties. To give shooters what they want, engineers at Savage Arms Inc., Suffield, Conn. (savagearms.com), developed AccuTrigger for their company's rifles. It lets shooters adjust trigger pull anywhere between 1.5 to 6 lb. It is safe in that it cannot accidentally discharge even at the lowest setting. Users only need to remove the stock and turn the trigger-return spring with a tool supplied with the rifle. The device includes AccuRelease, which blocks the sear and prevents the rifle from firing unless the AccuRelease lever is fully depressed. Tests show that AccuTrigger is smoother, crisper, breaks cleaner, and has less creep that any factory-built trigger.