Invector / Standard Invector Choke Tubes.
Browning was one of the original innovators in developing choke tubes designed to increase versatility of a shotgunner's barrels. Now a hunter or shooter could easily change tubes (and the pattern) without changing barrels. The original Browning Invector Choke tube system -- often called Standard Invector -- was extremely innovative for hunters and clay target shooters, allowing a fast, convenient and effective system for adjusting the pattern to the game/target and distance.
The Invector Choke Tube system utilized barrels with internal threads to screw in chokes of the shooter's choice. A wrench was supplied to facilitate removal and installation of tubes. Popular choke constrictions were offered, including Extra Full Turkey tubes and rifled chokes for deer hunting, using Sabot, slugs or heavy buckshot. This was a game-changer for the industry. Today nearly all shotguns have interchangeable choke tubes.
The original Invector (or Standard Invector) is currently found on Browning shotguns with threaded choke tubes in 10 gauge, 16 gauge, 28 gauge and .410 bore -- for primarily Citori and BPS shotguns.
These are some of the basic features of the Standard Invector choke system.
Standard Invector™ tubes are available in constrictions ranging from Cylinder to Extra-Full
Produces excellent patterns with excellent uniform densities
All Browning Standard Invector choke tubes are set to industry constriction standards
Flush fit does not extend beyond end of barrel
Thread-first design offers a seal against carbon build-up and makes removal and insertion easier than some other designs which are prone to fouling
Constructed of highly polished, 17-4 stainless steel for the ultimate in performance and durability -- both in blued and polished stainless finishes
Standard Invector is still considered one of the top choke tube systems available and is used on 10 gauge, 16 gauge, 28 gauge and .410 bore. The length of a .410 bore tube creates -- in effect -- an extended tube, and by proportion is one of the longest tubes available.
Invector-Plus and Invector-DS are used on most of Browning's high performance 12 and 20 gauge models where the need for more specialized, ultra-performing tubes is required.
The Tech-Term "Standard Invector" is referred to in the following products: