This is a post I typed up elsewhere.
My standard suggestion for improving the trigger is the Clark hammer bushing, Volquartsen sear and trigger.
The Clark hammer bushing & sear pin kit (CLK517 for a 22/45 IIRC) is oversized and eliminates some creep. Creep is the play in the trigger once the pretravel is taken up, but before the sear breaks.
The VQ sear reduces trigger pull.
The VQ trigger has pretravel and overtravel adjustments. The Ruger trigger action is single action, 2 stage. This means there is a lighter first stage, then the trigger breaks with additional pull. A little pretravel is needed for the action to reset. I like to minimize it for the shortest possible trigger stroke.
Overtravel is movement of the trigger after the sear breaks. The only real downside is a longer movement to reset the action.
With those 3 parts the trigger pull comes in around 2# 4 oz, very crisp, and under .100" travel (typically .090" total stroke).
The Volquartsen hammer reduces lock time. The amount of time between the sear breaking and the bullet firing (think flint lock delay). I cannot detect a benefit, and while I have one or two guns with one in it, won't buy another. That said if the gun in question isn't a Target model from Ruger (adjustable sights typically) the VQ hammer will have more benefit as it will reduce creep slightly also.
The Volquartsen titanium disconnector is a couple ounces lighter than the steel Ruger part, but no one I am aware of, my self included, has been able to detect a measurable difference with a trigger scale. However it does offer an improved location for the trigger pin, which reduces pretravel. They have since replaced it with a steel one but I have not handled one.
If your gun is a MkIII, I highly suggest the Clark or another MkII hammer bushing to eliminate the magazine disconnect safety. This modification also allows magazines to drop free when the button is pushed, and makes them easier to insert. This also allows you to use the less expensive MkII hammer/accurizing kit should you choose to.
