Mobius wrote:That seems to be a Ian Hoggism. I have his book "British and American Artillery of WWII" and it has 1/25 for the M5 as well.
But it is 1/40 or 1/32 for M1A2 in Handbook of Ballistic and Engineering Data for Ammunition. Volume 2
http://oai.dtic.mil/oai/oai?verb=getRec ... =ADA955369
It's probably off topic from the thread, but the M10 and 3 in ATGs had a greater powder charge than the M1 series (76mm) of guns. The 76mm cartridges were full and the 3 in cartridges actually had 'dead-space' inside them where
more powder could have been packed. IF the 3 inch had a higher velocity (some say 2800 fps), THEN the 1/40 rifling may not have been as detrimental. The 76mm cartridges were modified with a longer flash tube inside in late war production to address the smoke issue. Whether this effected MV, who knows. Again, off topic. But interesting that two weapons firing the same projectile, with similar length/rifled barrels could do so with such a difference in powder weight, and supposedly attain the same velocity?