At trial, CE-399 would most likely be determined to be admissible. Most evidence, if the only issue with it is a questionable chain of custody, is indeed admissible. It is then left up to the jury to decide how much weight to give a certain piece of evidence with a questionable chain of custody.
The trial judge would admit the bullet. A questionable chain of custody of CE-399 may affect how much weight the jury gives the bullet but a questionable chain, on its own, does not affect it's admissibility.
The single bullet that passed through both Kennedy and Connally and ended up in Connally's thigh must, at some point, be found somewhere. Even if this bullet was NOT CE-399, it is a must that this bullet would be found by someone somewhere. No other bullet has ever been found (in Connally's thigh or elsewhere). Even if you do not believe in the single bullet theory, the fact remains that a bullet lodged itself in Connally's left thigh.
To any conspiracy advocate, especially the original poster of this thread, have you ever seen any evidence put forth which suggests that a bullet, other than CE-399, was found inside Connally's thigh or anywhere else related to the known movements of the bodies of both Kennedy and Connally?
On the night of the assassination and overnight into Saturday morning, the limousine was searched by the FBI. They were looking for evidence. Smaller fragments were found but no intact bullet, like 399, was found. No other bullet has ever been turned in and placed into the record and this circumstantial evidence alone gets 399 admitted into evidence.
It's up to the jury to decide, based on a questionable chain of custody, how much weight to give CE-399 as the bullet found at Parkland.
Also, it is up to the defense, since CE-399 was linked to Oswald's rifle to the exclusion of all other weapons in the world, to convince the jury that CE-399 was NOT the bullet found at the hospital. Has anyone in this forum (or anywhere else) done so?