UPDATE: I just called Hornady and spoke with a tech about the issue. The facts so far are as follows:
1) They are claiming that a small bit of movement "rattle" is normal.
2) I informed them that I can load up my buddies SST rounds, which are from a 4 year old lot number, and they fly straight and make clovers at 50 yards. His 4 year old slugs are tight and have absolutely no movement inside the sabot or shell.
3) I informed them that the rounds I purchased are making 12 to 16 inch diameter (6 to 8 inch radius) groups at 54 measured yards.
4) They are sending me a pre-paid UPS Shipping label so that I can return some boxes and some empty shells to them for testing. Testing is a bit backlogged and can take up to 3 weeks but should be done sooner.
5) I asked the following questions and DID NOT receive definitive answers: a) If the slug is loose and wobbling inside the sabot, how can the rifling impart positive spin if it is slipping? b) If the slug is loose and wobbling, and the tip of the slug exits the barrel and or the sabot at slightly different angles due to the wobbling, how is it possible that it could fly the same way for each round?
When I called Hornady, the wait time to get to a tech was almost zero. They picked up the phone pretty darn quickly and the guy tried to answer my questions the best he could.
I'm going to be very interested to see what happens here.. I've blown quite a bit of money on ammo and am discouraged at the unreliability of my expensive toy.