"When you use .44 magnum or the Mysterious Magnum in 3rd person view, most of the time you will miss the target, even while you're aiming, therefore making it better to use this gun in 1st person view."
Quote from FalloutWiki.

This bug really bothers me a lot since I always like to play in 3rd person view and Mysterious Magnum is one of my favorite weapon. All weapons use this animation have the same problem - first shot will always miss where I aiming. Also, I added .50 DE into the game with .44 animation since the recoil of this hand cannon is really strong and very suitable for this animation; but later I found the same problem, too. Changing it into 9mm pistol animation would solve the issue but that would make this gun way more too over powered. So I'm guessing this bug is not caused by the guns, it's caused by the animation. Is there anyway to solve this issue?

It's a glitch imbedded in the game itself. Had the same problem, but thought it was WAR that was causing it. After a full day of troubleshooting, still didn't have a solution. Sorry.

@bft90679 use this mod http://modsreloaded.com/aiming-fix it "Fixes: .357 Magnum, Lucky, .44 Magnum, Mysterious Magnum, Hunting Revolver, Ranger Sequoia, Sawed-Off Shotgun, and Big Boomer." i always have this mod installed regardless if i use any of the said weapons.