You don't need a bullet for setting headspace.
You can...
full size a virgin case,
tape 2 pieces of masking tape on the head,
snug the barrel up to it,
remove the sized brass,
tighten the barrel nut.
Now you'll be limited to this brass and sizing die only,... no one can tell how much a FL sizing die will size compared to a go-gauge.
You could use just the virgin brass with out sizing it but who knows how far off it's going to be compared to when you FL size it.
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