The problem with the assumption that Jack Ruby planted CE399 on a stretcher at Parkland Hospital is that the actual bullet retrieved by hospital engineer Darrell Tomlinson was of a different colour and shape. According to Mr. Tomlinson, the bullet that he found on the stretcher was grey and and had a pointed tip. His superior, former police officer O.P. Wright confirmed that.
CE399 is copper-coloured and has a rounded tip.