Mike - I thought you were saying the longer 300's create a better gas seal, elevating barrel pressures and would therefor show greater velocity from the same sabot/charge combination. I guess that wasn't your point but leaves me wondering why you posted that target? ( I was expecting to see higher fps with the 300's)

The spinning top is an interesting description. What would you say if you put the 200's thru a chrono from the White and found 2000+ fps? Still wobbling? I think so, but not because they aren't spinning fast enough but because they are being pushed too hard. Faster than the spin rate can stabalize. Just a thought. Suppose you took the White again and used 80 T7??