Effect of barrel and trigger location?

[wasatch]

Does a lower barrel (with respect to the hand) and trigger closer to the barrel make for a more forgiving pistol?

For instance the LP400 looks to have a barrel that is low compared to the grip and the trigger is quite close to the barrel--there is little frame separating the trigger from the breech. Whereas the K12 barrel looks high compared to the grip and the trigger is quite a ways below the barrel--there is quite a bit of frame between the barrel and trigger.

Does a trigger close to the barrel reduce effect of snatching or other poor trigger technique by having less leverage? And does a lower barrel cause the recoil to drive more directly back into the hand whereas a high barrel might flip more?

[shaky hands]

Does a lower barrel (with respect to the hand) and trigger closer to the barrel make for a more forgiving pistol?

Lower barrel line -- definitely so, the more the barrel is inline with the forearm, the weaker the muzzle flip is going to be.
Trigger closer to the barrel -- less clear.

For instance the LP400 looks to have a barrel that is low compared to the grip... Whereas the K12 barrel looks high compared to the grip...

I fail to notice that, to me they look (when I look at the actual pictures of shooters holding LP400 and K12) very similar. Besides, with the recoil practically eliminated in K12 there would be no muzzle flip to worry about to begin with.

Does a trigger close to the barrel reduce effect of snatching or other poor trigger technique by having less leverage?

Trigger position with respect to the barrel is not determinative per se, the leverage should be calculated with respect to the center of mass of the whole "pistol+hand" system. Ideally, a trigger pivot should be right at the center of mass, that would eliminate rotational torque. But the whole thing is so shooter-specific that it would probably be hopeless to try to establish any meaningful hard and rast recommendations here.

[therider]

a trigger pivot should be right at the center of mass, that would eliminate rotational torque.

Not the trigger pivot, but the point where the force is applied.
However this is only true for "free" body mass.

As the pistol is not a free body, the point of application of the trigger force should pass through the 'hinge' of the pistol with respect to the hand (assuming that the possibility of rotation is not completely removed, e.i. an elastic fixation). But where is the hinge? May be the pivoting point is the "ball" which sits in the cup of the hand?

[shaky hands]

a trigger pivot should be right at the center of mass, that would eliminate rotational torque.

Not the trigger pivot, but the point where the force is applied.

Upon further thought, you are right here, though with qualifications. Had there been a rigid connection between the trigger and the pistol your statement would always be true. For an actual pivot and a very slow trigger squeeze it would also be true, as the full torque would be transferred to the pistol trough the pivot. However, for a sudden acceleration of the trigger (as in the classic trigger jerk) it is probably something in between: some part of the torque applied by your finger gets transferred to the pistol though not all of it. What fraction? Who knows.

However this is only true for "free" body mass.
As the pistol is not a free body, the point of application of the trigger force should pass through the 'hinge' of the pistol with respect to the hand (assuming that the possibility of rotation is not completely removed, e.i. an elastic fixation). But where is the hinge? May be the pivoting point is the "ball" which sits in the cup of the hand?

And the position of the effective "hinge" would also depend on the tightness of the grip and the efficiency of wrist locking. It gets too fuzzy very quickly. In a trigger jerk unlocking the wrist probably plays even more role than the additional force on the trigger itself.