I have a 24V .30WCF over 20 gauge that I never could get good accuracy out of, and of course could never get the barrels regulated. So I decided to make a "mountain survival" carbine out of it. I cut the rifle barrel to 19.5", and the shot barrel to 18.75". As there seemed to be a good bit of pressure between the muzzles of the barrels I attempted to bore out the portion of the front band that the rifle barrel went through, but it "crumbled". What the heck is it made of?? So what I did then was make it into kind of a "cradle" with the rifle barrel lightly resting on it.
That helped with regulation, brought the slugs up quite a bit, but slugs still print low, so I put a flip-up-flip-down rear sight on it. That way, with the sight up, it's sighted for the rifle barrel, flip down and hold the front sight all the way up, and two little screws on the sight for windage, she's only a hair low at 25 yards, with windage right on. My main purpose for the shot barrel is for close in defense against big critters that would scratch or bite me. No plans to shoot slugs over 25-30 yards. In the future, I may dove-tail in another flip-up and get her sighted with slugs to 50 yards.
Oddly enough, with bird shot loads the pattern is "on", maybe a hair low, but nothing a grouse or rabbit will notice. Even with the wide open sawed off shot barrel, it throws a nice 25 yard pattern without any holes in it. Perfectly fine for the deep woods. The accuracy of the rifle barrel is nothing to brag about, but she'll bag a deer out to 100 yards in case I were to get that hungry in a survival situation. It's nice and light and "handy", easy to carry, and between slugs, rifle loads, light rifle loads, 20gauge slugs and shot loads, she covers a lot of bases. I usually pair it up with a light .22LR pistol.
Just noticed I posted about this gun before. Oh well. Have done some upgrades to the sights since then. (sights and minimum pressure between barrels) And, after giving the action a good cleaning it does not break open on firing with the .30-30 barrel.