No need...just shoot soft lead pills out of 44/40 WCF cartridges! They chamber perfectly....and squeeze down the bore.

Some people with a penchant for poaching Hog Deer here in Victoria have been given to this relatively lo-noise and inexpensive strategum.

But..once again...you didn't hear this from me!

Alternatively,...get .44 cal barrels sleeved into .410 shotgun barrels and chamber it for 44/40...you don't even have to modify the extractor... a very low cost route to a small calibre double rifle.