no no no no
do not take it back
all you need do is trim 2mm off the 303 full length die and trim 2mm off your 303 cases, full length size with 7.7x54 die and you have a 7.7x54
or get a 303 reamer down the chamber
the 7.7x54 is a shortened 303 case that's all
but get the shop to either: rechamber to 303 or get the full length die and seater turned down for you
or simplex sells dies for it get the shop to buy you some dies
simplex engineering pty ltd, 02 97581280
the shop does have responsibility as the seller, but try and do it amicably, think before you speak
I think they didn't know
have a good christmas
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