As you've found out, those bullets are made for the .45 Long Colt or .45 ACP.
The design has no heel to start into the chamber.
Also, since it's cast for cartridges using smokeless powder, it's probably the wrong alloy for black powder.
You need very soft, almost pure, lead for use with black powder.
You also need the right lubricant. Lubricants designed for smokeless powder lack the moisture required to keep black powder fouling soft.
A proper black powder lubricant will be SPG, Lyman Black Powder Gold, or a homemade lube that uses two or more of: Crisco, beeswax, lard, mutton tallow, vegetable oil, whatever.
The lubricant must be natural, not based on petroleum products. Canning paraffin is an exception to the petroleum prohibition, for reasons uncertain.
Petroleum products, when used with black powder or its substitutes, tend to create a hard, tarry fouling.
If you bought bullets made for reloading .45 cartridges with smokeless powder, they are likely too hard an alloy, and contain the wrong lubricant.
Take them back or trade them.
Dixie Gun Works sells cast, soft lead, unlubricated bullets of the Remington or Colt cap and ball original design.
The original design had a short heel that slipped into the chamber to help align the bullet. The bullet was also very stubby, to give ample clearance under the rammer.
The bullet mould that Colt made for the 1860 Colt had a groove around it to hold lubricant. I believe this was the first Colt conical design to feature this, but could be wrong.