If you go to the CMPwebsite, you can find their phone number & ask if they any record of your rifle's SN. DCM was the predecessor to CMP, but I don't know if DCM sales were added to CMP's data base. If they have a record of your rifle, they will send you written verification for $5.
DCM/CMP paperwork actually adds to the value of a rifle, as there are quite a few "restored" & fake A4's out there.
Neal