I could have sworn I had written about these, but I can't find a post about it now, so apologies if this is mostly a rehash (and now that I think on it some more, I may have only posted it on a Dark Conspiracy message thread elsewhere).
Back in 2018, Gun Jesus did a
video on a Szescei & Fuchs double-barrel bolt-action rifle. Intended for dangerous game hunting, it provides a quicker follow-up shot than a conventional bolt-action with higher ammunition capacity than a tradition double-barrel. Poking around on their website, I found they fall into 7 cartridge sizes: varmint rounds (.17-.22), .30-06, 8x68mm S, .375 H&H Magnum, 9.3x62mm Mauser, .416 Remington Magnum, and .470 Capstick. The Remington Magnum has both side-by-side and over-under configurations, the 8x68mm S is only an over-under, and all the others are only side-by-side. For the Hummingbird in small calibers, I only figured stats for .22 Hornet, which is the most powerful of the available rounds. These are absolute show pieces with engraving and plating and all sorts of decoration, so possibly appropriate for a very rich character to have. While marked as BA for rate of fire, they should be allowed 2 fire actions at SA before having to reload; if only 1 shot is fired before reloading it will eject a live round, since the bolt cycles both barrels' actions simultaneously. The magazine numbers all have "+2" to indicate that both barrels can be carried loaded along with a full magazine.
Hummingbird (5.6x35mm, .22 Hornet)
Wt 3.5 kg, ROF BA, Dam 3, Pen 1-Nil, Blk 7, Mag 8+2, SS 3, Rng 63
Lion’s Dream (7.8x63.1mm Springfield .30-06)
Wt 4.4 kg, ROF BA, Dam 5, Pen 2-3-Nil, Blk 8, Mag 6+2, SS 4, Rng 69
Blue Boy (8x68mm S)
Wt 5.2 kg, ROF BA, Dam 5, Pen 2-4-6, Blk 8, Mag 4+2, SS 5, Rng 75
Elephant’s Life (9.6x72.4mm .375 H&H Magnum)
Wt 5.2 kg, ROF BA, Dam 6, Pen 2-4-6, Blk 9, Mag 6+2, SS 6, Rng 82
Russian Five (9.3x62mm Mauser)
Wt 4.3 kg, ROF BA, Dam 6, Pen 2-4-6, Blk 9, Mag 6+2, SS 6, Rng 83
Big Five Royal Blue / White Tiger / African Queen (10.6x72.4mm .416 Remington Magnum)
Wt 5.2 kg, ROF BA, Dam 7, Pen 2-3-4, Blk 9, Mag 6+2, SS 7, Rng 90
Mokume / Celtic (12.1x72mm .470 Capstick)
Wt 5.4 kg, ROF BA, Dam 8, Pen 2-3-4, Blk 10, Mag 6+2, SS 7, Rng 103