The 115 gr Silvertip did meet the FBI penetration/expansion requirements at that time. It's just that the FBI's protocol was completely different than what it was after Miami. Prior to Miami the FBI was pushing the RII and their computerman model. That was all about rapid expansion/limited penetration. It was after the Miami shootout that the FBI changed their requirements.
With the FBI nearly everything is a pendulum. They swing to one side, then people change positions and they swing to the opposite side. Rarely do they settle in the middle.
Here's some history.
My agency issued the same 115 Silvertip in 1980. Remember now that everyone, including the FBI, was preaching rapid expansion/limited penetration as the optimum rd. During a shootout in Joliet IL with a biker the Silvertip performed exactly as it was designed, ie, rapid expansion/limited penetration. The biker who was wearing a leather vest over a leather jacket was hit 11 times in the torso from a distance of about 20 ft (length of the squad car). None of the rds penetrated to the vitals nor would have been fatal. The biker died but it was from a heart attack from clogged arteries due to his less than healthy life style. We immediately pulled the Silvertip from service and went with the Federal BP, later BPLE.
A few years later the FBI decided they were going to the 9mm. Our range guys took the file of our Joliet shooting to Quantico to show the FBI our results of the Silvertip. The FBI didn't care. They sent our guys packing. The FBI "knew" what was the best round because they had the formula, ie RII, and their famed computerman which proved the Silvertip was the best round. There was no discussing it with them. It didn't matter that at that time we'd already been using the 9mm for 20 years, had about 2000 9mm on the street doing the job, and had more shootings with the rd than the FBI over a period of many years. We had the street results. The FBI had a formula and a computerman. They didn't want to hear about what we had learned. Street results didn't matter, they had "science" to prove their point. About a year later Miami happened and the FBI learned what he had learned 6 years previous and had tried to show them. The difference is our people went home afterwards.
P.S. Кто не в теме, читать можно тут:
https://warhead.su/2018/08/08/gollivud-otdyhaet-zhivye-mertvetsy-protiv-tolpy-agentov-fbr
https://warhead.su/2018/12/09/promah-s-desyatkoy-kak-fbr-oblomalos-pri-vybore-patrona