The term for grooves on a coin's edge is reeding.
Reeding was introduced to stop the practice of "shaving" coins back when they contained silver or gold. Crooks would use a knife or file to remove small amounts of metal from the edges of a lot of coins and then sell the shavings at a profit. If the edge is smooth it is much harder to detect shaving, so reeds were put on the edges to make it more obvious when someone had tampered with a coin.
Today reeding isn't needed to prevent shaving, but it has become useful as a way for people who are blind to tell the difference between coins with similar diameters. For example, dimes and cents are almost alike in size but cents have smooth edges; same thing for quarters and dollars. Regarding euro, which has 8 regularly-circulating coins, unusual patterns are used to distinguish among coins that are otherwise essentially the same size. 50-eurocent coins have coarse reeding, €2 coins have fine reeding and €1 coins have "interrupted" reeding; i.e. there are alternate patterns of smooth and grooved sections along the edge.
No. The barrels are not rifled
Yes, the barrels are rifled.
Neither barrel is rifled.
Not safely
You can, but I wouldn't advise it.
Slugs! If its rifled it is a deer hunting barrel.
Yes. That's the only type of shotgun you should fire a sabot slug from. Rifled shotguns are intended for rifled slugs only. Actually, the opposite is true. Rifled slugs are preferred for smooth barreled shotguns. The 'rifling' on the slug is actually just fins that permit the slug to squeeze through the choke on the shotgun barrel. Sabot slugs are intended for rifled barrels, as they will give better accuracy. Some sabots may be used in smooth barrels, but you are paying more for sabots and not getting the accuracy you would get by using a sabot in a rifled barrel.
Look inside. If it has lands and grooves, it is rifled. If it does not, it is smooth
Do they now? Some tanks have certainly had rifled-barrelled guns.
Rifled slugs may be safely fired thru MOST shotgun barrels, The makers of some variable chokes recommend that slugs NOT be fired thru them, and turkey guns that use the Extra Full choke aer not usually recommended for slug shooting.
You look down the barrel and if it is swirled it is a rifled barrel and if it is not swirled it is a smooth bore
A rifled cannon can shoot approximatly 500 yards. The rifled cannon is a great weapon. I advise you to use it(if you have one) in a space between 600 and 700 yards.