Below is a factory loaded Winchester .303 case that stretched and thinned .009 on the first firing.



This same batch of cases started separating after the first reload, when full length resized.



The problem with these Winchester cases were thin rims and headspace that allowed the case to stretch.

The reason I'm posting this is because Prvi Partizan cases were the best cases you could get for reloading the .303 British. And Winchester cases were the worst and why I sectioned them to show the thinning.

Bottom line, proper fire forming on the first firing and letting the case headspace on its shoulder thereafter prevents the case stretching. And this is a problem with many type Hornet cases.



Below a properly fire formed case that headspaces off it shoulder.



On the first firing if you seat the bullet long and jam the bullet into the rifling this will hold the case against the bolt face, and the case will not stretch. A Enfield rifle at maximum military headspace of .074 and a case with a rim thickness of .058 you would have .016 head clearance.