Here’s an interesting article on the Remington EtronX – a gun that uses no sear pin, and instead substitutes a piezo electric module. From Popular Mechanics:
Consider it a shot in the arm for factory sporting rifles. Remington’s new Model 700 EtronX centerfire target rifle and pesky varmint bagger is more than just another gun. It’s the opening salvo in what could well be the next revolution in firearms. What Remington has done is take the mechanical trigger and related hardware required to energize and release the firing pin of its standard Model 700 and replace it with an electronic trigger and an electronic, versus the usual percussive, ignition system. Why? In a word–accuracy. In two more words–simplicity and reliability.
On the accuracy side of the equation, the longer it takes between the time you squeeze the trigger and the time the bullet exits the muzzle, the less your chances are for achieving a dead-accurate shot in long-distance shooting. A significant factor in this is lock time, or the interval between the instant the trigger releases the firing pin and the point of sufficient impact of the firing pin to detonate the primer.
In a percussion rifle, the normal lock time is anywhere from 2.8 milliseconds on the fast end up to or exceeding 7 or 8 External appearances aside, the inner workings of the new Model 700 EtronX are nothing short of revolutionary. milliseconds. The biggest variable here is in the trigger mechanism itself. A fast system typically consists of a trigger that pulls out from underneath a sear and releases a striker, or firing pin, which is driven forward by a mainspring. In a slower system, the trigger mechanically releases a hammer that pivots about an arm and reaches up to strike the firing pin, which in turn starts to move and then impacts the primer. A few milliseconds here or there may not seem like much, but when you’re aiming and pulling the trigger, the muzzle tends to move around a bit. All things being equal, shorter lock time reduces off-target barrel movement. As we mentioned, this applies primarily to long-distance shooting. Short- and medium-distance target accuracy remains largely unaffected by lock time.
Another drawback of percussion firing is the harmonic vibrations that the firing pin impact sets up in the barrel. While heavier barrels tend to absorb more of these vibes than lighter barrels, this mild shake can still factor into bottom-line accuracy.
The EtronX system is turned on and off by a removable key located in the grip cap. The key can be removed in either the On or Off position. The trigger is basically a switch that sends a signal to the 8-bit computer tucked inside the synthetic stock. So, in other words, this is the first machine with its brains in its butt. Trigger pull is adjustable from a factory setting of 2.3 pounds down to a half-pound. And, unlike mechanical triggers with friction and wear between moving parts, the EtronX with no moving parts gives you pulls that are smooth and consistent, with 36 percent less travel than the standard 700. Lock time for the electronic firing circuit is slashed to 27 microseconds. That’s a 99 percent reduction compared to the standard 700’s.