Powder Ignition Failure

[bombdoc]

I was always taught in my ballistics classes that the "all burned" point should be somewhere around 2/3 of the barrel length! This may apply more to large calibre artillery rounds, but I assume the same should be true for small bore..

Burn rate can change with ambient temperature and pressure, so if the "all burned" point is near to or outside the barrel, then inconsistent ballistics are surely inevitable?

Just for interest, I have just measured a Lebel case capacity.. maximum physical load for N140 is around 51 grains!