Yep, I got the blanks punch line...... A BFA would be no use with a straight pull rifle - no gas port. But keeping strictly on message, had a request as to why I asked about whether the jambing occurs with blank firing. Simple.
If the jambing DOES occur with blank, then it is a HEAT issue OR heat is a secondary issue. Secondly, because blank does not produce recoil* it cannot contribute towards the notion of the BB being jambed or lifted up hared against the underside of the BBC.
Heavens...., all this talk of blanks and BBC's.......
* to correct a myth. Blanks do produce a recoil but in discussions relating to weapons, it is so small as to be academic.