Choke Tube Identification

How to Choose the Correct Choke Tube System for Your Browning Shotgun

Three different choke tube systems have been offered in Browning shotguns: Standard Invector, Invector-Plus and Invector-DS. The choke tube systems are not interchangeable. Over the years, the same shotgun models and even the same gauges have been fitted with these three different choke tube systems. Each system is also used on various models of current Browning shotguns. Carefully read below and you won't make a mistake when ordering choke tubes for your Browning shotgun. 

Standard Invector Choke Tubes

Standard Invector Choke Tubes

The original Browning interchangeable choke tube system.  

  • Standard Invector choke tubes fit only shotguns marked Invector or Standard Invector.
  • They never fit shotguns marked Invector-Plus (+) or Invector-DS.
  • 10 gauge, 28 gauge and .410 bore Browning shotguns always utilize the Standard Invector system.
  • Most 16 gauge shotguns use the Standard Invector system, with the exception of the current A5 Sweet 16 models, which use the Invector-DS system. 
  • Multi-gauge sets, found on Citori over and under shotguns, will often include a combination of Invector-Plus (12 and 20 gauge) and Standard Invector (16 and 28 gauge and .410 bore).

Over the past 30 years, many products have featured the Standard Invector choke tube system. Extended choke tubes are available for Standard Invector, which because of their length make them appear similar to Invector-Plus choke tubes, but they are NOT interchangeable. 

Standard Invector stamped on shotgun barrel.

Look for a stamp on the barrel that says "Standard Invector" or often simply "Invector" as pictured above on autoloading and pump shotguns or on the monobloc of break-action shotguns.

Invector-Plus Choke Tubes

Invector-Plus Choke Tubes

Durable with excellent patterning, the Invector-Plus interchangable choke tube system has been a mainstay of Browning shotgun performance for over 20 years.

  • Barrels marked Invector-Plus (or Invector+) are not compatible and will not accept Invector-DS or Standard Invector choke tubes.
  • Invector-Plus choke tubes fit only Browning shotguns with Invector Plus (+) on the barrel(s).
  • They are found on many 12 and 20 gauge Browning shotguns.
  • Multi-gauge sets, found on Citori over and under shotguns, will often include a combination of Invector-Plus (12 and 20 gauge) and Standard Invector (16 and 28 gauge and .410 bore).

Invector-Plus choke tubes feature a longer design for improved pattern performance and are considered a significant breakthrough in choke tube design.

Invector-Plus stamped on shotgun barrel.

Look for a barrel stamp that says "Invector Plus" like the one pictured above on autoloading and pump shotguns or on the monobloc of break-action shotguns.

Invector-DS Choke Tubes

Invector-DS Choke Tubes

The newest and most advanced Browning choke tube system. 

  • Invector-DS choke tubes fit only Browning shotguns with Invector-DS marked on the barrel(s).
  • DO NOT buy these if your shotgun is marked Invector, Standard Invector or Invector-Plus (+).
  • The choke constriction technologies found on Invector-DS choke tubes improve pattern performance beyond what was previously thought possible.

Invector-DS choke tubes are much longer than other Browning choke tubes and have threads on the muzzle end of the tube. They also feature a bronze seal at the base of the tube that helps prevent fouling from being forced into the gap between the barrel and the choke tube, making the tube difficult to remove.

 

Invector DS stamped on shotgun barrel.

Look for a barrel stamp that says "Invector DS" like the one pictured above on autoloading and pump shotguns or on the monobloc of break-action shotguns.

Before Purchasing Choke Tubes

If you have any questions regarding which choke tube system is compatible with your shotgun, call our Customer Service department during business hours, 8:00 AM to 4:30 PM Mountain time.  TOLL FREE: 1-800-333-3288

In all cases, the type of choke tube your barrel has is indicated on the barrel and for new shotguns can be found under the "Features" listing on the product page on the Browning website. 

Choke Tube Systems Available By Gauge

Standard Invector, Invector-Plus and Invector-DS choke tube systems are NOT interchangeable.

10 Gauge

Standard Invector

12 Gauge

Standard Invector

Invector-Plus

Invector-DS

16 Gauge 

Standard Invector

Invector-DS
(A5 Sweet 16 only)

20 Gauge

Standard Invector

Invector-Plus

Invector-DS

28 Gauge

Standard Invector

.410 Bore

Standard Invector

The History of Browning Choke Tube Systems

Choke tubes are an integral part of a modern shotgun. When researching a Browning Citori or Citori 725 on the Browning website it is generally a good idea to confirm the type of choke each model is fitted with. Do this by looking on the barrel, the monoblock, on the choke tubes included with the shotgun or on our website by clicking on the model and looking under "Features." 

This is a good start, but due to the fact that some models have multiple barrels in multiple gauges, it can become much more confusing. The confusion is due to the very nature of multi-barrel sets and due to the act of producing sub-gauge models in versions based on 12 gauge models. Given that many of us love multi-gauge sets and sub-gauge over and unders, understanding the process is worth the time and effort. 

The special issue of multi-barrel set shotguns. Multi-gauge/barrel sets are like the custom cars of the firearms business. They are not a run-of-the-mill product that is mass produced by the millions. A bit of customization is exactly what most customers want. The act of fitting all barrels makes them very close to custom. Therefore, it should be expected that a higher level of uniqueness will exist in what you purchase and that you will get a higher level of customization for your money. When shopping for firearms at this level of design and quality, it pays to spend some extra time learning about the features before you make your purchase. 

If you are new to shotgunning, and in particular Browning shotgunning, it is important to know that none of the choke tube systems produced by Browning are interchangeable. They all have their own histories in the Browning timeline of new features development over many years and they all fit a specific purpose. That being said, all Browning choke tube system designs are still relevant and effective today.  

Browning has produced three different basic choke tube designs since the end of the fixed choke era:

Standard Invector (or Invector)
A very early introduction in the marketplace.

Invector Plus (or Invector +)
A longer tube with improved pattern performance.

Invector-DS
A totally new concept in pattern performance and a breakthrough in creating a better tube-to-barrel seal.

All are currently available in extended versions which protrude beyond the end the the muzzle when screwed tightly in place. This means that determining the type of Browning choke tube system by length is not possible, or at best can be totally confusing. Refer to the inscription on the choke tube and match it up to the inscription on the barrel of your shotgun.

There are choke tubes within each of the three systems designed for specific purposes such as steel shot or turkey hunting, for example. For detailed information on the different types of Browning choke tubes available, click here.

Multi-Gauge Sets

Multi-gauge sets are shotguns with matched sets of barrels with different gauges. Browning makes over and under shotguns with multiple barrel sets fitted to a single receiver. The points below are essential for you to choose the correct choke tubes for a multi-barrel set. 

  • In all cases, the 16 and 28 gauge and .410 bore barrels in multi-gauge sets will be STANDARD INVECTOR for all Browning shotguns.
  • Generally, 12 and 20 gauge barrels in Citori 725 sets will be Invector-DS.
  • Generally, current 12 and 20 gauge barrels in Citori (non-725) sets will be Invector-Plus.
  • Many older sets might be Standard Invector (beginning way back the 1980s), but no current sets.
  • There are no 10 gauge barrels in multi-barrel sets. 
  • For special builds and other specials, there may be exceptions. Always check the barrel first to know which system to use before purchasing. 
  • The variations may seem confusing, but these sets are built in response to customer requests over time and will not always be consistent. This will not be a problem if you  always check the barrels first to make sure you know the choke tube system that is compatible with each barrel or barrel set. 

The choke tube system will be identified:

  • On the barrel or monobloc
  • In the "Features" listing on the Browning website 
  • If you are unable to locate this information, please contact our Customer Service department.

Always Double Check

Errors in online and printed literature. Due to the sheer volume of information found in Browning printed and digital literature it is possible that errors in specifications will occur. Occasionally, an error in clarity in our printed or online information will occur. Sometimes a product change is simply missed in the effort to get the new information to you, our customers. Since many multi-barrel sets are "specials" made virtually "to order" the actual specifications for the model may not be known until well after the model is announced. Before making an expensive purchase of multi-barrel sets, or if you have any questions at all about the choke tube system your shotgun is fitted to accept, call our Customer Service department for clarification.

Browning Customer Service
One Browning Place
Morgan, UT 84050
TOLL-FREE:    1-800-333-3288

If you have any additional insights or desire clarification for any of the above we welcome your input. 

Identifying a Choke Tube's Constriction or Pattern Rating

Browning choke tubes use several systems for identification. Some are useful in the field, and others when the choke tube is out. Choke tubes supplied with your Browning shotgun often have notches in the top edge which can help you determine the choke constriction. Generally you will need to remove it and read the inscription on the side of the tube.

GENERAL ABBREVIATIONS

(as found on product listings)

DESCRIPTIONS

XF

Extra Full

XF TRAP or X-FULL TRAP  

Extra Full Trap Shooting Choke

X FULL TKY-TRAP

Dual use Extra Full tube for turkey or trap shooting

X FULL TKY

Extra Full Turkey Hunting Choke

F

Full

LF or LFULL

Light Full

IMOD or IM or IMP MOD or I MOD

Improved Modified

MOD or M

Modified

LMOD or LM  or LT MOD or L MOD

Light Modified

IMP CYL or IC  

Improved Cylinder

SK or EXT SKT

Skeet

CYL or C

Cylinder (sometimes incorrectly abbreviated to CLY)

SPREADER

Special tube with a form of "rifling" that spreads the pattern rapidly, for close-in upland hunting

RIF DEER

Rifled Deer Tube (for shooting slugs, primarily sabots)

 

 

NOTCHES IN RIM OF TUBE 

(OEM Invector and Invector Plus, not found on extended tubes)

I

Full lead or steel, but may be too tight for good steel performance

II

Modified lead, Improved Modifed Steel

III

Improved Cylinder lead, Improved Cylinder Steel

IIII

Skeet lead, Modifed Steel

NONE, no notch

Cylinder lead, Improved Cylinder Steel

 

 

SPECIALTY DESIGNATIONS

 

LONG

Tight constriction tube used for longer ranges, mostly referring to steel shot

MED

Medium constriction for medium ranges with steel shot

CLOSE or CLOSE RANGE

Very open choke tube used for close range shooting with steel shot

 

 

OTHER ABBREVIATIONS

 

WF

Waterfowl

TKY

Turkey

INV PLUS

Invector-Plus Choke Tube System

INV

Invector Choke Tube System (Standard Invector)

EXT

Extended choke tube that extends beyond the muzzle

INV DS

Invector-DS Choke Tube System

TNT

Timber and Teal (helically spun to spin shot)

Average Pattern Percentages

Measured using the number of pellets in a 30" circle at 30 yards. Varies with shot size and/or lead vs. steel shot. Steel patterns generally exhibit a higher percentage of pellets inside the circle.

IMPORTANT: The following values are approximate. They vary between gauges and the type, length and design of the choke tube. 

12 GAUGE

75-85% – Extra Full Trap
55-85% – Full
30-60% – Light Modified
45-75% – Improved Modified
35-65% – Modified
30-60% – Light Modified
25-55% – Improved Cylinder
20-45% – Skeet
15-45% – Cylinder
Very open – Spreader

20 GAUGE 

55-85% – Full
45-75% – Improved Modified
35-65% – Modified
30-60% – Light Modified
25-55% – Improved Cylinder
20-45% – Skeet 

Abbreviations and Constrictions for Browning Invector-DS Choke Tubes

INVECTOR-DS CHOKE, 12, FULL 75-80%
INVECTOR-DS CHOKE, 12, LIGHT FULL 70-75%
INVECTOR-DS CHOKE, 12, IMOD 65-75%
INVECTOR-DS CHOKE, 12, MOD 55-65%
INVECTOR-DS CHOKE, 12, LMOD 45-55%
INVECTOR-DS CHOKE, 12, IC 40-45%
INVECTOR-DS CHOKE, 12, SK 35-40%

INVECTOR-DS CHOKE, 12, FULL, EXTENDED 75-80%
INVECTOR-DS CHOKE, 12, LIGHT FULL, EXTENDED 70-75%
INVECTOR-DS CHOKE, 12, IMOD, EXTENDED 65-75%
INVECTOR-DS CHOKE, 12, MOD, EXTENDED 55-65%
INVECTOR-DS CHOKE, 12, LMOD, EXTENDED 45-55%
INVECTOR-DS CHOKE, 12, IC, EXTENDED 40-45%
INVECTOR-DS CHOKE, 12, SK, EXTENDED 35-40%