Even though they are called bridge pickups, they are not specifically for the bridge position. In BK's sets they are matched to the neck pickup, but when pickups were first introduced there was no such thing as a bridge or neck pickup. Even through the 60's into the 70's, if you needed a replacement pickup, you just ordered the type, not the position. Only when DiMarzio introduced their pickups did you start to see a hotter wind for use in the bridge position. This doesns't mean that hotter bridge pickups didn't exist, they were just accidents though. I remember many years ago messing around with 6 early 60's strat pickups to find the best set for a 63 Strat. Each of the pickups was slightly different. The removal of humbucker covers was in part to try to get a hotter bridge pickup, as the pickup is brighter, slightly more sensitive and can be put slightly closer to the strings with the cover removed.