I can't comment on accuracy with rifled choke tubes as I have not tried them. Some people say they work well but I have to think that if they did then there would be fewer rifled barrels.

My feeling is that the twist is too fast and rifling too shallow for them to work well but I could well be wrong as that is all that seems to be available. No reason not to try it though.

One comment I have read several times is that the choke tubes tend to torque in so tight they are very difficult to remove so watch for that. This mostly with full bore slugs I think.

Several people on this site, nitroexpress and shotgunworld have worked up slug loads for side bys for the same reason but often use smoothbore slugs or plain old round balls in smoothbore. Accuracy can apparently be reasonable to 50 yards.

I have been working towards a poor man's Paradox gun... very slowly! My original intent was to have a side by slug gun but I find I am occupied enough by trying to get decent smoothbore slug groups at long range from single barreled guns much less side bys! Good groups at 50 yards are not hard to come by but much beyond that they are work!

If you do try it I suggest 0.690" round balls in Federal wads or BPI has a 0.690" balll load in one of their wads. TRG3 has posted good results with 0.690" ball in wad in a fully rifled barrel. Alternately, 0.735" balls should work fine. I have shot many through smoothbore (cylinder bore) and one fellow here adam64 IIRC said he got good accuracy with 0.735" RBs and rifled tube.

I am leaning towards the 0.678" RB in shotcup for smoothbore but I doubt it would be tight enough fit for rifled gun. You need some squeeze or the slug may slip.

Just my $0.02.

Longbow