DWs were case hardened internally, one of the reasons its a bad idea to monkey with the guts trying to slick them up.
I'd guess some "shade tree gunsmiff" cut through the case hardening & tried some plating to fix the mistake.
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Allan Quatermain: “Automatic rifles. Who in God's name has automatic rifles”?
Elderly Hunter: “That's dashed unsporting. Probably Belgium.”
