Why does older powder data often show a greater powder charge as a max load than newer data?
Better instrumentation? Increased knowledge of properties of steel? Legal issues?
This is data from IMR in 1990:
1990 IMR Data
For example, in new data from Hodgdon, powder
charge is 3.2 grains less than old-
270 Win 130gr, X grains of IMR4831, 3003fps 50,300 CUP 24" bbl
Old data from IMR:
270 Win 130gr, X + 3.2 gr IMR4831, 3110fps 53,600 CUP 23" bbl (1" shorter)
So why the change?
Thanks in advance.
Better instrumentation? Increased knowledge of properties of steel? Legal issues?
This is data from IMR in 1990:
1990 IMR Data
For example, in new data from Hodgdon, powder
charge is 3.2 grains less than old-
270 Win 130gr, X grains of IMR4831, 3003fps 50,300 CUP 24" bbl
Old data from IMR:
270 Win 130gr, X + 3.2 gr IMR4831, 3110fps 53,600 CUP 23" bbl (1" shorter)
So why the change?
Thanks in advance.