I've posted this before but, this is what I've found on the MP/DC Purple SOLID cams:

Their advertised durations use timing events @ .015"

I typically find, duration @ .020" is 8º less. i.e. 312/590 cam is 304º @ .020"

Duration @ .050" is 32º less than duration @ .020"

So the 312/590 cam looks like this:

304º @ .020"
272º @ .050"

I hope that helps.