Get you a First Wave X-45 pistol.
Its the only one that can have all the attachment slots. Plus, its frankly the best pistol stat wise.
Hard to argue with 600RpM and 33 round magazine with all the attachments.
Every other pistol in this game is so beyond useless that id rather have a dull butter knife over any of the pistols.....
But even that one, sometimes I have the correct Small attachment for it yet it will not show on the list to put on the pistol.
Of course this depends on the game NOT crashing.
Then it is not the correct attachment for the weapon. It has been so long since I actually tried other pistols, but I also use the X45 pistols and mostly for this reason. It has all the slots available and can use any "small" attachments.
In case you are newer to the game, I'll also mention that some other pistols will have what appears to be a higher base stat. But, due to them not being able to fill the extra attachment slots, any benefit is lost. Adding crit hit damage and chance to pistols does help a lot. BTW, don't bother with the exotic pistols.