Well. Curiosity finally got me and I asked DOL for a copy of my records. They returned a copy of my Firearms Purchased Certification record. They will do this for any walk-in (Olympia DOL) or at your CLEO upon request. They want two forms of ID. (360) 664-6616.
This Certification is a list of all handgun purchases reported to them (Dealer or otherwise) that they still show to you (ie, you didn't sell and report to them as transferred to another.) They did say they could provide a list of all historical purchases upon request. They also stated they routinely deal with requests for this information daily from LEOs, DAs and most any other .GOV investigation being pursued.
Below is a marked-up portion of my list (several pages omitted
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I suppose this list could be helpful in attempting to prove ownership or such, perhaps for insurance purposes.
Thought you'd all find it interesting!