Choke tube markings are a series of lines, notches, letters, or numbers that help identify the size of a choke tube. The letters ER are usually written on the outside walls of the choke tube, and it can be confusing if you haven’t seen it before.
ER stands for EXTENDED RANGE. It designates the choke tube constriction size and in this case ER is an Improved Modified with regards to tightness. It measures 0.695” in diameter in fixed choke 12-gauges.
Extended Range chokes are used for dove and waterfowl hunting and they help provide effective patterns at distances between 30 and 40 yards. If you see “ER” written on a choke tube, you can be sure it’s tighter than a Modified choke.
What does ER mean on a choke tube?
Choke tube letters designate what diameter a choke tube is and ER is included in these designations. ER stands for Extended Range and is the diameter of an Improved Modified.
Popular Extended Range choke tubes include:
Some chokes can be labeled as EXT Range and this means Extended Range as well. This designation is brand specific and isn’t related to the standard naming scheme. Extended Range will be listed as ER, EXT, or Extended Range. ER chokes should not be confused with Modified choke tubes.
What is the diameter of extended range chokes?
Improved modified diameters differ based on shotgun brand and choke system. Below is a chart showing the diameter of ER chokes by brand.
| Type | ER Diameter (inch) |
| Beretta/Benelli Mobil | 0.696 |
| Benelli Crio | 0.697 |
| Beretta Optima Plus | 0.702 |
| Benelli Super Sport | 0.697 |
| Beretta Optima | 0.702 |
| Browning Invector | 0.797 |
| Invector Plus | 0.710 |
| Remington | 0.697 |
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.
What are ER choke tubes used for?
ER choke tubes pattern tighter at long ranges. They are ideal for shots on waterfowl out to 40 yards. They work best with steel shot on ducks and geese by producing more consistent results.
Improved Modified chokes aren’t a popular choke size and aren’t included in choke sets for new shotguns. However, the performance of Improved Modified chokes between 30 and 40 yards is worth the investment.
Are ER choke tubes open chokes?
Extended Range choke tubes are tighter than Modified and but more open than Full chokes. While they aren’t considered an open choke tube, they are designed for longer shots. 50 yards is usually the max distance with steel shot through an Extended Range choke.
Improved modified chokes excel with steel, especially smaller shot between #6 and #2. They also can be used with TSS shot which delivers devastating downrange patterns for waterfowl and turkeys.
Bottom Line: ER Means Extended Range
ER stands for Extended Range. The letters ER will be written on the side of the choke tube. Improved Modified is the closest comparable choke size to Extended Range. Extended Range chokes perform in between that of a Modified choke and a Light Full choke.
Improved Modified chokes are great for long range waterfowl hunting with steel shot. They can also be used with magnum turkey loads for shots up to 50 yards.
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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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