Hi Sesuko,
How are you doing, you're hard to satisfy, the Large Military Firesteels that we just received a new batch off are 3/8" diameter and about 2.3/4" long, this without the plastic thumbpiece,layard,striker.
The Scout model we have (we only have some left!) are 1/8" diameter and 1 5/8" long again without the thumpiece, lanyard,striker
I had one Scout model that had snapped the Ferrocium of just at the thumpiece and yesterday evening I squared it of and drilled a 1/16" hole through one end. WOW you should have seen those hot sparks flying/forming where I drilled it. The sparks were so abundant

that they lighted a normal piece of pinewood that I used as a base in the dril clamp thingy, no need for scrapes and slivers of the wood it just lighted it.
So I hard fireworks yesterday evening but now I have a nice 1 5/8" long 1/8" diameter flintsteel to attach to my keychain or stuff in a small survival kit.
Sesuko, you can use a hacksaw and cut the ferrocium rod from the thumbpiece of either the Large or Scout model Firesteel if you wish.
Best Scouting wishes from Holland,
Bagheera