I have to admit it sounds like the kind of BS I can imagine some of the gun shop owners I have met and shooters selling their rifles on the secondhand market will have used. But I very much doubt that any of the well known and successful tuning companies would bother with such nonsense.
PS not all gunshop owners and private sellers are prone to BS!
PPS surely you would only need to select the best if you were tuning cheaper makes with poor QC? I think SMK claim their supergrade/deluxe models are specially selected and fettled in the UK. Could this be what you are recalling?
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