Here is some info,
“Special prosecutors dismissed an involuntary manslaughter charge against Baldwin in April, saying they were informed the gun might have been modified before the shooting and malfunctioned. They later pivoted and began weighing whether to refile a charge against Baldwin after receiving a new analysis of the gun.
The analysis from experts in ballistics and forensic testing relied on replacement parts to reassemble the gun fired by Baldwin, after parts of the pistol were broken during testing by the FBI. The report examined the gun and markings it left on a spent cartridge to conclude that the trigger had to have been pulled or depressed.
The analysis led by Lucien Haag of Forensic Science Services in Arizona stated that although Baldwin repeatedly denied pulling the trigger, "given the tests, findings and observations reported here, the trigger had to be pulled or depressed sufficiently to release the fully cocked or retracted hammer of the evidence revolver."
An earlier FBI report on the agency’s analysis of the gun found that, as is common with firearms of that design, it could go off without pulling the trigger if force was applied to an uncocked hammer, such as by dropping the weapon.
The only way the testers could get it to fire was by striking the gun with a mallet while the hammer was down and resting on the cartridge, or by pulling the trigger while it was fully cocked. The gun eventually broke during testing.”
So the fuck sticks at the FBI didn’t get the result they wanted so they beat on the gun until it broke and gave them the results they wanted which resulted in his initial dropped charges due to a faulty firearm.