Choke tube markings are a series of lines, notches, letters, or numbers that help identify the size of a choke tube. Choke tubes with 1 line usually appear on the top of the choke tube and it can be confusing if you haven’t seen it before.
1 line means FULL CHOKE. Lines indicate the size or constriction of the choke tube. A Benelli choke tube with 1 line (I) is a Full choke. Beretta shotguns that use Mobil chokes will also show 1 line to indicate Full choke constriction.
Browning choke tube markings are the same as well, where 1 line means Full Choke Lead or Full Steel. The line markings on a choke tube can be found etched into the top edge of the choke.
What does 1 line on a choke tube mean?
1 line on a choke tube indicates the size or constriction of the choke tube. A Benelli choke tube with 1 line (I) is a full choke. Beretta shotguns that use Mobil chokes will also show 1 line to indicate full.
Browning choke tube markings are the same as well, where 1 line means Full Lead or Full Steel. The line markings on a choke tube can be found etched into the top edge of the choke.
Full choke diameters differ based on shotgun brand and choke system. Below is a chart showing the diameter of Full chokes by brand.
| Type | F Diameter (inch) |
| Beretta/Benelli Mobil | 0.686 |
| Benelli Crio | 0.687 |
| Beretta Optima Plus | 0.692 |
| Benelli Super Sport | 0.687 |
| Beretta Optima | 0.692 |
| Browning Invector | 0.687 |
| Invector Plus | 0.700 |
| Remington | 0.687 |
More Choke Tube Markings
There are over 30 different choke tube markings used for choke identification. Below are the most common markings. Please click the links below to see what each choke tube marking means.
Why are lines used on choke tubes?
Choke tube lines are notches that are gouged into the choke to identify the choke size without needing to remove it from the shotgun. Lines on choke tubes feature 5 standard choke sizes including Full, Improved Modified, Modified, Improved Cylinder, and Cylinder.
The lines on most chokes are marked at the edge of the top of the choke (opposite the threads) and are deep gouges that can’t be easily removed. Choke tube lines appear as I, II, III, IIII, and V.
What if a choke tube doesn’t have any lines?
Some aftermarket choke tubes with customized choke sizes do not have choke lines. The diameter of the choke is typically etched onto the side of the choke instead.
Subsequently, most factory choke tubes do have choke tube lines which adhere to the manufacturers marking guidelines. Popular Browning, Benelli, and Beretta choke tube markings are listed below.
Browning Choke Tube Markings
I – Full Lead or Steel
II – Modified Lead, Improved Modified Steel
III – Improved Cylinder Lead, Modified Steel
IIII – Skeet Lead, Light Modified Steel
None – Cylinder Lead, Improved Cylinder Steel
Benelli Choke Tube Markings
I – Full
II – Improved Modified
III – Modified
IIII – Improved Cylinder
V – Cylinder
Beretta Choke Tube Markings
I – Full
II – Improved Modified
III – Modified
IIII – Improved Cylinder
V – Cylinder
One line on a choke tube is always the tightest constriction for that brand of choke. It denotes a Full choke. 2 lines on a choke tube range between Modified and Improved Modified and are slightly more open than chokes with one line.
1 line chokes are universally Full chokes with steel shot and four lines are Improved Cylinder or Skeet. Some manufacturers use stars or dots instead on lines, but the premise remains the same.
Bottom Line: 1 Line Means Full Choke
1 line on a choke tube means that it’s a Full choke. A full choke tube is one of the tightest diameters, just behind that of Extra Full and turkey.
Full choke tubes with 1 line work best for long ranges of up to 60 yards for ducks, geese, and turkeys. Lines on a choke tube can be found etched into the top of the choke tube.
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Related
- Complete Guide to Identifying Choke Tube Sizes
- Choke Tube Diameter and Constriction Table
- What do the numbers mean on a choke tube?
- Ultimate Guide to Shotgun Pellet Sizes
- What does 3 lines on a choke tube mean?
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