List it on the big auction site starting at $.01 (penny auction) and see what it goes for. I agree that putting it back original would bring the most $$.
Do the same for the accessories. Don't get too worried if the top bids don't come in till the last couple of hours. It should bring at least $250 on the low end but most likely more. The accessories dont have much value but the "high cap" and even the rifle itself may go up significantly after the election depending which way the winds blow. Just be sure not to ship to a "restricted" part of the country and make that plain in the ad.
I often use the big auction site to determine current market value of items but you have to look at closed auctions. The ones where the item actually had bids and sold, not at asking prices. The penny auctions always sell and are a pretty good reflection of the current market.