Thanks Spook I will try the AA 1680

Trail Boss loads
 

I bought a can (8 or 9oz as opposed to a 1lb) and decided to start with the .223 loads. This is because Hodgdon has load data for it in .223, .308 and a couple others. Hoping that this would give me a feel for the powder before moving to .300-221.

In the AR platform with Hodgdon's recommended loads it managed to 'stick' 2 out of 3 cases in the chamber and nowhere near starting to cycle. I've drawn my conclusions that while TB and RedDot type volumes may be okay for single shot... I'm sticking with slower burn rates for AR.