I used a pure conti grip topspin forehand for 5 years, my first 5. After my 3rd, I found it hard to pass A/Open net players using a pistol grip, so one of them showed me a more hammer grip, to get the rackethead around faster, allow the natural snap of the wrist to accelerate the rackethead, like a service motion (nobody pistols, but uses light hammer). It worked.
Pistol like McEnroe/Connors gives him the control, not the swingspeed. Guys who conti forehand topspin with pace and spin use a high prep, racket pointed up at the sky on the takeback, which is a result of the hammer grip. Or a high, long loop takeback, same modified hammer grip.