I remember many years ago a lot of fellows did that,and even someone came out with a sabot for it( that is what we used them for anyway),it looked like the cup end of todays sabot on both ends.Think this was before the black powder subs came out because I remember shooting a nice 8 pointer with this set up in a 45 cal kit gun I put together.and I was useing black powder.Think they quit making the sabot because they thought they were dangerous.If I looked around hard enough I could probably find one.Seems like they were tan in color.
Maybe some of you old timers can remember these.

POLY PATCH

don't seem like either ball would get asmuch range or acuracy as if they were fired as a single. but im just guessin? i don't really know.

early

Several of the people in my group[our club] did it for several years including me you had to work out a different load to get accuracy my particular load put two 45 cal balls about 1 inch apart. It had some serious knock down power worked well on deer.
THEN one of the guys ended up with a bulged barrel since I had built the rifle and did most of the repair work for the guys we set out to find out what happened. To make a long story short one of the experiments I set up showed that the air trapped between two PBR could push the last one loaded back up the barrel causing an obstruction. We made a rule against shooting them on our range and wrote TC a letter suggesting that with tightly patched balls and a rifled barrel it could be dangerous. Lee

Double ball loaded ONE time. .45 TC Hawken, 90 grains of Pyro P and two patched balls stacked. Knocked tha livin el outa me, recocked the rifle (not half-cocked.. full cocked), and bloodied my mouth.

Don't care to repeat that act. Based on that one experience, the recoil from shooting a big heavy conical is extremely mild by comparison.

I sure wouldn't try it. I would guess some of the recoil/bore pressure would depend on how tight those patch & balls are - plus the slipperyness of thelube used. Some guys use a hammer to knock their roundball & patch down the bore. They want the tightest fit possible. That'll raise the recoil level some.

"THEN one of the guys ended up with a bulged barrel since I had built the rifle and did most of the repair work for the guys we set out to find out what happened. To make a long story short one of the experiments I set up showed that the air trapped between two PBR could push the last one loaded back up the barrel causing an obstruction. We made a rule against shooting them on our range and wrote TC a letter suggesting that with tightly patched balls and a rifled barrel it could be dangerous."

Yep. Loading two balls in a ML rifle is definitely in the "not recommended" category....... For those who will try it anyway, dump in the powder, then start the first ball, push it flush with the muzzle, then start the second ball touching the first one, then ram them down TOGETHER so no air is trapped between the balls to push them apart after seating them.....

I do not see any reason to do that.

[ul][*]You have a chance of something or someone getting hurt[*]You use double the lead which would cost more $$$[*]Remember, roundballs loose velocity and energy fast, with two roundballs you get less velocity and less energy in the first place so it would not be good at all at long range.[/ul]