You can, but you should be careful about the chamber length. For example, the most common length for modern 12 gauge shells is 2 3/4", but older shotguns may only be chambered for 2 1/2" shells. So long as the chamber length is ok, it is certainly possible to load and shoot black powder with modern hulls. Appropriately sized plastic wads can also be used (I've used Winchester red AA wads with AA hulls, 80 grains of powder, 1 oz. of shot). You do tend to get some stringy plastic residue that has to be cleaned out of the bore. I've actually switched to using brass shotshells for black powder now.
Your Iver Johnson will shoot rocks if you want. the biggest and single most issue you need to keep in mind is the breech pressure modern loads produce. most antique guns utilized black powder as opposed to modern smokeless powder and with that your comparing apples to watermellons. through the company "Balistic products" they specialize in shotgun paraphenaila and offer many books and products to safely relaod black powder shells fire antique shotguns.
Yes, but beware that many blank shells contain corrosive gun powder. Clean your shotgun after firing blanks to avoid pitting your barrel.
No. Only black powder shells can be used, and even than, it may not be safe to shoot. I load my own with 2 drams of 2f real black powder and 7/8 oz of shot. Have a gunsmith take a look at the gun first.
Yes
Shotgun shells
Shotguns are the primary firearm type that fire shells. Certain shotguns will chamber and fire shells that are 3 inches long.
Shotguns fire shot shells. Handguns can fire specially made shotshells.
12 gauge shells.
gun powder
Yes, definitely, always, without exception. Pyrodex or similar powders which equal the characteristics of black powder may be used. Significant danger to the shooter and the gun will result if smokeless powder is used. Note many folks who know that their Damascus barrels are sound shoot modern shells through their guns. I have shot thousands of Winchester AA Feathers through my Damascus Daly. These shells have lower pressure that many black powder rounds.With a gun this fine you should join the DoubleGun BBS a place where old guns are talked about every day and shot alot. Also check out the German Gun Collectors website. Never shoot every day wally world shells but modern low pressure shell can be found without much trouble.
YES IF ITS MARKED 3 INCH, THEY NEVER MADE BLACK POWDER SHELLS IN 3 INCH FOR 12 GA GUNS.
yes they can be but you will need a blunder buss