Saboted canister shell help

[Cthulhu]

I want to create a sort of "canister" or "grapeshot" round for my cartridge combustion Spud Howitzer that can rain paintballs at a distance.

While I know that I could probably just fill a paper cup with paintballs and put it behind a wad of some sort, I want to get better performance, ideally a spread that is effective at a distance of 100 feet.

To test this, I have come up with this shell. It's essentially a wad made of EVA foam with a paper disk that is cut and folded (as in the diagram) and filled with paintballs. To keep this sabot together, a couple loosely tied pieces of yarn are wrapped around the middle and top (these will hopefully simply slide off in the barrel during firing). The top of the sabot has a tissue stuffed in it to prevent paintballs from falling out prior to firing, it too will fall off during firing with the sabot and yarn due to it's light weight.

Is this an effective design and is it any better than just a bunch of paintballs wrapped in a paper towel shoved down the barrel?

[jackssmirkingrevenge]

Is there a plastic/paper cup that will fit into you barrel?

[Cthulhu]

Is there a plastic/paper cup that will fit into you barrel?

It's a 3" bore so not quite. I can always make a paper cup to operate as a cup sabot instead of the expanding cup sabot I have designed now. Think that'll work better?

[Sear]

There is another risk you should be aware of when designing paintball canister rounds. During the acceleration the upper paintballs will crush the lower ones and your shot becomes messy and ineffective. I'm not saying this is guaranteed, just that there is high risk that it will happen. Especially in big bore gun like yours 76mm one where you can stuff 100+ paintballs in one shot easily.

Better try it first with paintball-filled non-discarding sabot to see whether paintballs survive the launch.