Thank you, Daryl. That is useful. Pretty sure the Black Powder Express bullets were grease grooved. The Holland mould design shows multiple ridges facing forward to hold the paper against the bore. In this Lancaster tapered oval bore, the grease grooves serve the purpose of allowing the bullet to "give" and a place for the moved lead to go as it swages down the bore. A solid bullet could fit well near the chamber, but end up busting the muzzle on exit. Creating lots of margin for safely fitting to the bores and muzzles is how this gun is coming back to life. Also, the barrels are thin on these doubles, not nearly as strong as the heavier single shots. Boy would I like to see a Lancaster .450 BPE mould. Especially for the 1880s. Probably looks a lot like the "Gould" hollowpoint. The Lyman mould for this bullet casts a .457 grease groove bullet.