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Might be worth tracking down a .223 go gauge because if that doesn’t fit they can’t possibly argue anything.
If Tikkas have a weakness, it's in chambering quality. On average, they're very accurate guns but occasionally, this is -despite- the chambering quality. My gunsmith has commented at times on this. He's modified esp fitted cans on many hundreds of them.
Checking with a go gauge probably won't tell you anything if the problem is in the freebore/throat.