Invector was Brownings original choke tubes that came out in 1983. Invector Plus came along later for the back bored barrel shotguns. They are not interchangeable. Invector Plus= late model shotgun, Invector = earlier design shotgun. Both are still available for purchase.
* Full *- Improved Modified ** Modified **- Improved Cylinder **$ Skeet *** Cylinder Bore
Improved cylinder
The Invector, or "Standard Invector" system" was introduced in 1983. A few years later, the Invector-Plus chokes were introduced to fit the new back-bored shotgun barrels. These two choke systems will not interchange. If you have screw-in chokes in your shotgun barrel, the kind of system you have will be stamped on the barrel near the receiver. You must use the proper choke system for your shotgun.
Yes, as long as it has the right choke for slugs (cylinder or improved cylinder), the vents will make no difference to the slug, and will reduce recoil slightly.
from smallest pattern to largest: full improved modified modified improved cylinder cylinder (no choke)
Browning Choke Markings "* " = full "*- " = improved modified "** " = modified "**-" = improved cylinder "**$" = skeet "***" = cylinder
I don't think there is an invector plus model. Invector Plus is the choke system Browning uses on newer shotguns.
M=MODIFIED IC=IMPROVED CYLINDER S=SKEET F=FULL Also, as stamped on receiver: * Full *- Improved Modified ** Modified **- Improved Cylinder **$ Skeet *** Cylinder Bore
ONE = Full TWO = Improved Modified THREE = Modified FOUR = Improved Cylinder FIVE = Cylinder
Browning did not make an Invector model. That is the type choke system of the shotgun.
Slugs will shoot safely through any choke but Improved cylinder or full cylinder should work.