File:Lancaster oval bore rifling.jpg - Wikimedia Commons
Polygonal Rifling
Lancaster Bore Russian Sporting Guns - Revivaler
NPS Interpretive Series: Artillery Through the Ages
Combination gun - Wikipedia
Gun - 68 pounder Lancaster elliptical-bore (1854) - Royal Armouries collections
GUNS. Rifling; Prussia; Jeffery, Britten Lancaster; Armstrong Shunt French 1880
Rifling
How does rifling work? - Quora
British Lancaster's Patent Oval Bore "Sappers & Miners Carbine"
So many ways to skin the cat. | vring
These Are Also Shotguns! (Please give your opinion in the survey) | The Sporting Bookworm's Hermitage
Rifling
Firearms History, Technology & Development: Is it a shotgun or a rifle? Oval Bores and the Colindian
Update: Russian 9.6x53mm LANCASTER Cartridge -The Firearm Blog
British Lancaster's Patent Oval Bore "Sappers & Miners Carbine"
Rifling
How can the rifling inside the gun's barrel induce the bullet to get rotation after shooting, but the surface of a bullets is very smooth? - Quora
New Russian 9.6x53mm Lancaster Cartridge and .366 TKM News -The Firearm Blog
Update: Russian 9.6x53mm LANCASTER Cartridge -The Firearm Blog
Charles William Lancaster - Wikipedia
LANCASTER 12 "COLINDIAN"- BALL & SHOT OVAL BORE RIFLED GAME GUN- 1895- 1964 BIRMINGHAM NITRO PROVED 30" STEEL Bbls.- .040" WALLS
Faceted bore gun
