Thanks for the reply, not often I question you but are you sure the “head stamp” was used by Frank Dyke?
I know that Frank sold a cartridge brand called the Shamrock, primarily on German made cases and of all bore sizes, this supply of course ceased with the onset of WW2 and Eley-Kynoch, Greenwood and Batley were later used.
Below some of the various sizes and colours;
Cooppal also supplied 410 cartridges with the Shamrock brand name, probably post WW2 looking at the case and primer.
Now we all know that he was renown for NOT putting his name on cartridges he loaded for himself and for others, which is a great shame as he was probably the biggest second tier supplier of cartridges in GB and there is a lot we do not know about him all of his premises and records were lost to bombing in the second world war.
Fede, do you have any record of that head stamp belonging to Frank other than the association of the trade mark “Shamrock”, sorry but I just have my doubts.
Jim, do you have anything that relates to this please?