Here is the roller coaster
"Speer 3" 1959 44 mag 240 gr. JSP..........23.0 gr. 2400 1564 fps
"Speer 6" 1964 44 mag 240 gr. JSP..........23.0 gr. 2400 1564 fps
"Speer 7" 1966 44 mag 240 gr. JSP..........23.0 gr. 2400 1564 fps
"Speer 8" 1970 44 mag 240 gr. JSP..........23.0 gr. 2400 1521 fps
"Speer 9" 1974 44 mag 240 gr. JSP..........19.5 gr. 2400 1344 fps
"Speer 10" 1979 44 mag 240 gr. JSP&MSP 22.2 gr. 2400 1392 fps.
"Speer 11" 1987 44 mag 240 gr. JSP&MSP 22.2 gr. 2400 1452 fps
"Speer 12" 1994 44 mag 240 gr. JSP&MSP 17.7 gr. 2400 1271 fps
"Speer 13" 1998 44 mag 240 gr. JSP&MSP 21.0 gr. 2400 1434 fps
"Speer 14" 2007 44 mag 240 gr. JSP&MSP 21.0 gr. 2400 ???? fps
That is a 30% variation.