Have just picked up this string.
When I bought my Rapid 2 FAC in 2001, it came with a warning label from Theoben not the dealer- saying, and I quote:
'WARNING Do not use Crosman Accupel. These pellets are causing many problems in some batches. Use H & N Trophy.'

I am reading directly from the label which came with my rifle. It is an accurate quote including the mis-spelling of Accupel (should be Accupell)
As I use BisMags or AA Fields I didn't enquire any further at the time.
Hope that helps.