These shells should have 9 guide lugs around the base that locate in the rifling when loaded. Neither the Tamiya nor the Armo aluminium shels have these.
Was not happy with previous attempt but this time I nailed it 
You will need:
Balsa wood jig - hollowed slightly to rest shell in
Fine copper wire - 1 strand from multi strand speaker cable is fine
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Cut the wire into roughly 10mm lengths - 9 per shell
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Stick the jig to the table at a rough 30 degree angle (blutack)
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Using the kit shell and some blutack, mark the lug positions on the shell
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Place shell onto jig, dip end of copper in CA and lay onto shell, parallel to table edge, thus creating the slight rifling angle on the lug
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Roll shell and repeat for all 9. I then took some more wire, made a small eye in it, dipped it in CA, and touched once on each ‘Lug’. This applies a minute extra amount around each lug to really fix it. Make a new ‘eye’ for each shell or it picks up too much CA eventually.
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With the shell on the jig cut each lug to the correct length with a curved scalpel blade in a rolling cut
7.Voila
