It may be because the decocker is down. If the decocker is not down, then something may be wrong with the gun.
Loaded or unloaded?
If you're referring to the US M9 pistol - the Beretta 92F - you can decock it simply by placing it on safe. The Beretta 92/M9 has a slide mounted hammer drop pin block safety which releases the hammer and blocks the firing pin so that the hammer won't strike it. If you want to actually CLEAR the pistol, you would put it on safe, drop the magazine, pull back the slide, inspect the chamber, then release the slide. I'd walk you through the functions check, but it's been too long.. Always point it in a safe direction before decocking. My 9mm has a decocking lever on the side, above the magazine release. Down decocks, up is the safety. You can also decock it by placing your thumb on the hammer, gently squeezing the trigger until the hammer is released, and slowly letting the hammer down. If your thumb slips off the hammer the pistol may fire, which is why you want it pointed in a "safe" direction.
You will have to call Beretta
Beretta does not.
Check the Beretta website.
Beretta Elite 2 has more power
Yes
50-800 Usd
Beretta 92F.
50-250
A copy of R. L. Wilson's book on Beretta will assist you.
Beretta made a LOT of different 9mm pistols. However, if you are asking about the M9 pistol used by the US Army, it is about 8.5 inches long.