? about steel shot

[Rifleman1776]

I know older shotguns should not be used with steel shot.
What I don't understand is 'why'?
I know steel is harder than lead and could damage a barrel if it comes into contact with it.
But, (most modern) shotgun shells encase the shot in plastic. Therefore no shot actually contacts the inside of the barrel. So, how can steel shot harm a barrel it doesn't touch?

[jmr40]

The barrels on many older guns was almost paper thin near the muzzles to reduce weight. When screw in chokes became popular the steel was left thicker to leave room for threading the barrels. The softer lead shot would conform to the barrels better as it went through the choked part of the end of the barrel. Harder steel shot will eventually lead to the end of the barrel splitting.

Manufacturers have also upgraded the toughness of the steel used in newer barrels with steel shot in mind.

Some older guns are OK with steel shot, many, especially doubles are not.

[Doyle]

Let me 'splain some shotgun physics to you. As the shot wad travels through the barrel it is constantly trying to expand. The barrel is keeping it from doing so. Then, all of a sudden, it hits the choke and gets squeezed down smaller than it started out being. Lead is nice and soft and deforms enough in the shot cup to go through the choke easily. Steel shot doesn't like being squeezed. It takes a much stronger barrel at the choke point to fight back that steel load's resistance to being squeezed.

It isn't the steel shot scratching the barrel that is going to do the damage. It is the extreme pressure just in front of the choke tube. If you ever see an old barrel that has been used for shooting steel shot, wrap your fingers around the barrel and run your hand down to the choke. You'll probably feel the bulge just before the choke.

[johnbt]

The word that's used is bridge, the shot bridges the choke. Lead is soft, steel isn't so there's a traffic jam. Instead of a row of uncompressible steel pellets trying to wedge through the muzzle/choke shoulder-to-shoulder, imagine the 3 Stooges trying to get through a door at the same time - not enough room.

[mete]

Between the non-deforming steel shot and thick plastic cup you get a tighter
pattern withe the steel than you wouls with lead in the same barrel and choke.
Always pattern your loads !!

[Rifleman1776]

Good explanations. Makes sense. Now I understand.
Thanks guys.

[Old Grump]

The slope of the cone going down to the choke diameter is longer and more gradual than the old chokes used for lead shot. That gives the steel room to ease into the tighter column instead of just being quickly forced down. Out of all my shotguns I have only 2 that I dare shoot steel in.

[baltz526]

Some old single barrel shotguns are safe with steel shot. remington has said there 870 and 1100 barrels with fixed full choke are safe with steel shot up to #2. no larger. Other single barrel guns with light chokes like imp cyl or modified will survive thousands of rounds of steel shot. As long as you shoot #2 steel shot or smaller. Then you get to the other problem with steel shot, shot smaller than #3 has little use unless your shooting small ducks over decoys. Large shot and full chokes is where steel shot has ruined a lot of shotgun barrels. If you have a specific shotgun in mind, related to your question. I bet someone will be able to give you an idea how safe it is for steel shot.