My first time experience with Incipient Separation

[Ovidio]

Quite a few years ago I noticed stretch marks on Enfield 303 cases I was reloading. I did some research and found that unlike rimless cases, the 303 headspaces on the rim. The British ream their chambers a bit deeper than they have to be . This causes the case to stretch a bit on firing. This has the advantage of allowing operation with dirt (think WWI), but if one full length sizes this pushes the case length back. Repeated a few times a one can get separation. The recommended solution was to separate cases by rifle, then neck size. I have done this and get great case life. To help even more you can put a thin "O" ring on the case just above the rim for the first firing. This makes sure the head is in firm contact with the bolt and eliminates the initial stretch.

Thanks for the advise!
I do the same thing with neck sizing and segregation, but the results are still the same.
I'll try now to keep track with my P14 about how many cycles a case can last. I have a full box of Sellier & Bellot and will keep notes.
I really like the rifles and the round. It is a pity that they have that problem (which is nothing big, just a bit expensive compared to all other rounds and rifles I shoot).