Can some one enlighten me , with the Beretta M92 ,9mm, which case does it take .... the 9x21 or the 9mm para case
Also for the 9mm which proj weight is the optimum
Regards

If it's a 9mm then it takes the 9mm case. The para is a 9mm. The 9x21 is a longer case than the 9mm (9x19). For reloading, folks typically use 125grain although I have tried everything from 115 grain (the old favorite), 121, 125, 130 and 145 grain bullets.
Peter.

so is the 9x19 the same as the 9mm parabellum
Daniel

Yes. Be aware however, that military rounds loaded for submachine guns are pretty hot loads from what I understand.
Peter.

Beretta pistols sold in Italy to civilians are the ones chambered in 9x21, as military cartridges are restricted. The overall length is the same, so the same mags can be used. Only the case length is different (it just covers more of the bullet).

It is rare to find a 9x21 pistol in the US, but some have made it over here. The 92 series is marked 98 if it is chambered for the 9x21.

KurtC, thanks very much. It makes sense that Berettas sold in Italy would have to be 9x21, but I had not thought of that. Do you know waht specs they are loaded to? I did not think that the Beretta had a ramped barrel. I have an EAA Witness in 9x21 that has a ramped barrel and I load it pretty hot.
Peter.

9x19 and 9x21 have the same ballistics, since they have the same case capacity (bullets are seated to the same overall length). The case will cover an extra 2mm of bullet, requiring a longer chamber. Everything else is pretty much the same.

Europeans load the 9x19 to higher specs than over here, so if they use the same formula for the 9x21 it will be slightly hot as well. Hope this helps.