Thread: Incremental load test anomalies

Originally Posted by Marty Henry

Loads where the powder is starting to be compressed often show a reduction in velocity. I'm buggered if I know why though.

It is the neck of the case there is only so much gas can flow through the neck of the case when the maximum flow rate is exceeded there is a bottle neck and the gas flow
can't flow fast enough and starts to swirl slowing down the gas and drops the velocity, I did some tests years ago and found as the powder charge went up the velocity
started to go backwards as much as 10fps for 0.5 grain increase .