Any reasonably competent 10-year-old can fire any pistol, given enough determination. However, accuracy is another matter entirely. It is not enough to merely fire a pistol: One has also to make a meaningful hit with it.
It is much easier to make the required hit with a pistol that has an easy-to-move trigger. That tends to rule out the Beretta M.92, because of its long, hard trigger pull. Instead, perhaps the child could use an old-fashion M1911, 45-caliber semi-auto, with its short, fairly light trigger pull. Remember, however, that before a shot may be fired from the M1911, its safety lever will have to be pressed down. (Once pressed, it stays down on its own.)
Another possibility would be to use the Beretta, but have the child cock (pull back) its hammer before attempting to shoot. Cocking this pistol's hammer converts it from its long, hard, double-action trigger pull to a shorter, lighter trigger pull more like that of the M1911.
The Beretta also has a safety lever, but many users leave it "off," and quite properly depend upon the long, hard trigger pull for safety.
Hitting a, um, target with a pistol's bullet is not as easy as TV shows make it appear to be. Most people cannot hit a man-size target that is only 20 feet away, with a pistol shot. Many people cannot do it at 10 feet. A child without experience would be very lucky to make a useful hit at five feet. Further, it is most unlikely that the child would be able to fire a follow-up shot, so make that first shot count.
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