Thanks Joe.
Gil - The Interceptors are really target loads (they only come in 8s and 8.5s to my knowledge), and the other two are specialty loads for vintage fixed choke guns, so I think they were developed for different reasons. Fiocchi at least does not suggest that the Interceptors were developed only for tight choked guns.
Note that Fiocchi also uses softer shot in their Spreader loads. From their catalog:
Spreader Loads Fiocchi Spreaders are available in 1 and 1 1/8 ounce versions for close target presentations. The 1 ounce Interceptor Spreader at 1300 f.p.s. is great for shooters who prefer 1 ounce loads. Two loads with 1 1/8 ounce (the Power Spreader at 1200 and the Rino Spreader at 1250 f.p.s.) offer loads with velocities common with other target loads (and similar target leads). Softer shot and purpose-oriented spreading wads induce larger patterns at shorter ranges for specific applications. These are great in single-barrel target guns when you cant change chokes between two targets. For example, if you encounter a pair of targets with the first shot close and the second far, load the Spreader to shoot first and follow up with your usual target load for the
longer shot. Problem solved.
As a practical matter, these results are consistent with the conventional wisdom that spreader loads don't help much with more open chokes.
