flintlock kit

[Turnup]

If only HE can have a detonation velocity then what is the term that would be used for the fast expansion of gases created when gunpowder explodes? It has obviously been measured for someone to arrive at the figure of 900-950fps. It must have some term attached to it for it to be understood.

That process is termed "deflagration". Google it and there is plenty of information out there