I believe it was a KMP sideplate built by an owner. That said, the firearm functions perfectly as far as I can tell. I've put about 50 rounds through it. The internals show only minimal wear and seem to have only been very lightly used by previous owners. For me, it has been more of a collectors item than something I brought with me to the range regularly.
Looking at your pictures, the bolt and top cover appear to be M3 rather than M2. And I can see signs of the M3 depressor on the left plate, so I think what you have there is an M3 receiver built into HB spec, which is the more common version these days. I don't follow the pricing on these anymore, but I hear rumors. It may be that your price is right in line. Its a nice package for someone.
As mentioned in some private messages, I'm willing to accept $10k without the custom barrel, and without the reloading equipment. Buyer must be outside of California. Shipping is possible, but likely to cost somewhere around $500. I'd only charge the actual shipping cost and FFL fees.
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