The Invector-Plus choke system is fully compatible with factory lead, tungsten, bismuth or steel shot loads. The conversion chart includes lead, tungsten, bismuth and steel shot information. Lead and steel shot perform differently in tubes with the same choke constriction. For this reason, both lead and steel designations have proven necessary. In fact, larger steel shot diameters result in different patterns than smaller steel shot sizes. Each designation is inscribed on each choke tube.
To help you choose the correct choke tube for each shooting situation, all Invector-Plus choke tubes are inscribed on the side with abbreviations for the patterns they produce with both lead and steel shot.
Each tube also features identification notches located on the top rim of each tube (Figure 18). These notches allow you to determine the choke designation while the tube is installed. Rim notches refer specifically to lead shot. You will need to use the chart on page 22 to cross-reference from lead to steel, and determine the appropriate tubes for your ammunition and hunting/shooting situation.
It is helpful to note that bismuth shot responds similarly to lead shot and tungsten shot responds more like steel shot.
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