Lu
I think that you will find that we aer talking about two different parts of the system. The AVPIN starter was ignited by a cartridge - think large shotgun shell but blank; it might have been a blank 50 cal. - that started the whole thing spinning, then the AVPIN started burning.
The starter turned at about 50K as I recall and had blades about the size of one's thumb nail. The starter was known to shed its blades so it wasn't a good idea to stand on the starboard side of the engine bay while the starter was running.