I really have a "thing" for odd action types...
...Particularly if they come chambered in a "finger-bore" cartridge. Bigger's lots more fun. More "thwack-factor", I think. And single-shots never run out of ammo. (Well, you never have to stop shooting to fill up some sort of magazine, anyhoot.
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So: most boyring, but still pretty neat is the old 71, or the 71/84 Mauser in 11mm Mauser.
Next up: Sniders. Love that flip-it-sideways breech. AND the .577 Snider!
I really like Martini/Henry's. (Or should I say Peabody?) Rourke's Drift. Zulu. The .577/.450, with iron case heads soldered to a case made of rolled brass foil. They look HORRIBLE! But they worked. 85 grains of blackpowder is a load to be reckoned with.
Favorite of them all is a pretty obvious choice: The Model 1873 Springfield Rifle, Caliber .45, also known as The Trapdoor Springfield, shooting that remarkable round-that-will-not-die, the .45-70 Government.
"In 1882, the bullet weight in the infantry rifle cartridge was increased from 405 grains to 500 grains in order to increase accuracy at extended ranges." That from the Ordinance Board. "Extended ranges" referred to barrage-fire by squads out to 1200 yards or so. The tang-sight on my 1882-vintage rifle is calibrated all the way out to 1500 yards!
(Out to 1200 on the front side, 1300,1400, and 1500 are marked out on the BACK side of the flip-up tang. I think I'm the only one who's ever noticed this, as NO-ONE talks about Trapdoors being sighted further than 1200 yards, not even Mike Venturino. I oughta send him a letter.
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Honorable mention to Enfields, Garands, k98 Mausers, and of course, Carl Gustaf's SwederMauser. But really, they don't compare.
Jus' throwin' out my $.02, fast an' loose...