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# How to use shotgun choke tubes — with a Fausti BC500 as the working example
- URL: https://being-prepared.ghost.io/how-to-use-shotgun-choke-tubes-with-a-fausti-bc500-as-the-working-example/
- Published: 2026-08-31T12:47:08.000Z
- Updated: 2026-08-31T12:47:08.000Z
- Author: Robert Yonaitis

A choke tube is a short constriction at the muzzle. It does not make the shot “hit harder.” It changes how fast the pellet cloud opens and how dense that cloud is at a given distance. Too open and you wound birds at 40 yards. Too tight and you miss the grouse that flushed at 18.

The names are the same whether the gun is a pump, a semi-auto, an over/under, or a side-by-side. The Fausti BC500 is a useful example because it ships with the standard five-tube field set most hunters actually get: Cylinder, Improved Cylinder, Modified, Improved Modified, and Full. Two barrels, five tubes, one wrench. Everything below applies to that set on almost any threaded shotgun.

**What the choke changes**

The barrel is a pipe. The tube pinches the last inch or two. Tighter pinch = pellets stay together longer = denser pattern farther out. More open = the cloud blooms sooner = more forgiveness up close, thinner pattern downrange.

Energy is still payload, velocity, and range. Choke only decides how many pellets arrive in the same 30-inch circle.

Catalog percentages (lead, 30-inch circle at 40 yards) are a starting point, not a promise:

| Tube              | Rough pattern at 40 yd | Typical useful range |
| ----------------- | ---------------------- | -------------------- |
| Cylinder          | \~30–40%               | 15–25 yd             |
| Improved Cylinder | \~45–50%               | 20–35 yd             |
| Modified          | \~55–60%               | 30–40 yd             |
| Improved Modified | \~60–65%               | 35–45 yd             |
| Full              | \~70%                  | 40–50 yd             |

Your barrel, your ammo, and your bead will disagree with the chart. Pattern the gun.

**How to identify the tube (Fausti and most Italian field sets)**

Notches on the rim, felt with a fingernail:

| Notches | Name                   | Italian | Role                        |
| ------- | ---------------------- | ------- | --------------------------- |
| 5       | Cylinder (C)           | 0/0     | Widest, closest             |
| 4       | Improved Cylinder (IC) | 1/4     | Close upland / decoys       |
| 3       | Modified (M)           | 1/2     | All-around mid range        |
| 2       | Improved Modified (IM) | 3/4     | Longer lead-shot work       |
| 1       | Full (F)               | 1/1     | Tightest factory field tube |

Other brands use stamps (C, IC, M, IM, F), colors, or writing on the body. If stamp and notches disagree, pattern it. Do not assume a “Modified” from Brand A matches Brand B.

**The five tubes, and when to use them**

**Cylinder**  
  
Almost no constriction. Closest work: woodcock in alders, quail in thick stuff, some skeet, and the default for many slugs. At 35 yards the pattern gets thin.

**Improved Cylinder**  
  
The workhorse upland tube. Grouse, early pheasant, chukar in cover, ducks that finish in the decoys. Forgives a rushed mount. On a two-barrel gun this is the usual first-shot tube.

**Modified**  
  
If you could only keep two tubes, many people keep IC and Modified. Mid-range pheasant, dove, rabbits, ducks that are not quite in your lap. On Faustis and many European guns, Modified is also the tightest choke the maker wants used with steel.

**Improved Modified**  
  
Longer crossing shots, late-season wild flushes, some trap. Easy to over-choke with. On Fausti tubes, treat IM as lead-only unless the tube or manual says otherwise.

**Full**  
  
Long passing shots with lead, some turkey work if you have patterned that exact load. This factory Full is not a dedicated extra-full turkey tube. Poor choice for a bird in your face. On Faustis, Full is lead-only for steel; steel through Full or IM can damage the tube and void the warranty.

**Two barrels versus one**

A pump or semi-auto has one choke for every shot. You pick the compromise.

A side-by-side or over/under (the BC500 is the former) lets you stage the shots:

- Tight cover: Cylinder / IC
- Walk-up upland: IC / Modified
- Open fields, later season: Modified / IM (lead)
- Mixed clays: IC / Modified

Put the more open tube in the barrel that fires first. Confirm which barrel that is on *your* gun — single-trigger SxS guns are not all the same — at the range, not on a bird.

**Shot versus slug**

**Birdshot**  
  
Match constriction to distance. Close and fast = open. Long and leaving = tighter. That is the whole game.

**Buckshot**  
  
Pattern it. Cylinder can throw flyers. IC or Modified often holds a tighter, more useful cluster. Room-distance “hallway sweep” patterns are fiction. Even Cylinder is a tight group at ten yards.

**Foster / Brenneke slugs (smoothbore, “rifled slug” on the box)**  
  
Use **Cylinder or Improved Cylinder**. That is the safe, accurate starting point. A little squeeze can help a Foster slug. Tighter than Modified is the wrong tool: you swage the slug, shift point of impact, beat the tube, and you do not gain a better deer gun.

Do not run slugs through Full or IM “because lead is soft.” Soft lead still has to pass a steel hole at speed.

**Sabot slugs**  
  
Those want a rifled barrel or a rifled choke made for them. A smooth Full tube is not a substitute. If the box says rifled barrel only, believe the box.

**Never fire a threaded barrel with no choke installed.** The muzzle threads are thin. One shot without a tube can raise a burr that ruins the barrel.

**Steel shot**

Steel patterns tighter than lead in the same tube. Fausti's manual: steel through Full or Improved Modified voids the warranty; do not go tighter than Modified (½ choke). If the tube is stamped “No Steel,” that is not optional language. IC or Modified with steel often behaves like a tighter lead pattern.

**Handling while you change tubes**

Works on a BC500, a 870, a Benelli, anything threaded:

1. Muzzles in a safe direction.
2. Action open. Both chambers empty. On a SxS with ejectors, do not look into the back of the action when you break it — hulls come out hard.
3. Then use the wrench.
4. Wipe threads. Light choke grease or oil. Dry steel galls, then the tube never comes out.
5. Seat by hand, snug with the wrench. Tight is not “as hard as you can.”
6. Recheck after a box or two. Heat and vibration back them out.
7. Spare tubes in the case pocket, not loose in a coat with grit.

Same firearm rules as always: finger off the trigger until the gun is mounted and the target is identified. Safety on until you intend to fire. Do not walk with muzzles covering the dog or the next hunter.

**The afternoon that makes the chart honest**

30-inch circle at 25 and 40 yards. The load you will actually hunt with. Each tube you will actually carry. Count pellets in the circle. See where the center sits relative to the bead. Some field guns shoot a little high — fine for rising birds, ugly for slugs if you did not know.

Write it down with the gun record.

**A working default**

Until you pattern it: **Improved Cylinder and Modified** for birdshot. Cylinder in the bag for slugs or very tight cover. IM and Full stay cased until the shot is honestly long and the load is lead.

On the BC500 that means one open tube and one mid tube in the two barrels, extras in the Negrini case. On a pump it means you pick one of those two and live with it until you change it.

The tubes are tools. Use the open one when the bird is in your face, the tighter one when it is leaving, and the slug-safe one when the projectile is a single piece of lead instead of a cloud.