When I complete "Bull In a China Shop", I immediately drive over to the train platform where the carbine rifle cop can spawn. During the drive, but before reaching the stairs, I shoot a cop, triggering a 3 star wanted level. This seems to always cause the carbine rifle cop to spawn. It has yet to fail me. The only downside is that unless you execute everything near perfectly, the next mission marker will appear before you get back, costing some time.
I remember many years ago viewing the beginning of a highlighted run which started just as the previous attempt was coming to a semi-disastrous close. Sometimes a VOD like this was accompanied by a remark signaling frustration or lost hope which, I suppose, the runner felt was a bit of amusing juxta
