bigcanadianbuckhunter,
There is a very good reason that you cannot find data for loading that hull in Winchesters load data. It's simply because Winchester DOES NOT recommend that this hull be reloaded, and therefore does not publish data for it's use. Just that simple.
That being said, you can reload the cases, but it should be limited to just once or twice, and the hull then discarded. THe hulls are too flimsey to be trusted for multiple reloads, and the base wads have a habit of coming loose with multiple reloads.
You can use AA data, as the internal shape and capacity of that case is very similar, and so reloads the same. Use this case only in reloads of moderate Chamber pressures, such as Target loads or Light Field Loads. Never use it in Heavy Field or Target loads with chamber pressures exceeding 10,000 PSI.
As for the 28 gauge, Winchester Ballistitions have determined that WSF has a tendancy to have pressure spikes which occur randomly and unexpectedly in this gauge. They therefore DO NOT recommend it's use in the 28 ga. and NEVER HAVE, since the powder was introduced on the market.
All I can say to you, or any other person using this powder in the 28 ga., "You are litterally taking a huge chance on damage to your guns, personal injury, and/or injury to others. If the Manufacturer and Distributor of this powder says "Don't Do It", then you are taking a huge risk in doing so.
To those who disagree with the above statements, there's no need for rebuttal. Facts are facts, and refusal to follow the recommendation of the manufacturer is simply, for lack of a better word, ludicrous.
Winchester's Ballistitions have the equipment to determine whether the powder is safe to use in certain usages. I dare say none of the ordinary reloaders have access to such testing equipment, and are simply loading by the seat of their pants.
DLM