ID Rimfire cartridges

Hello, I have posted about these cartridges a couple of times before but never had any luck, they are both the same diameter (I believe .27).
The larger one stands 9mm tall while the other is just shy of 7mm

One has the headstamp of “SI” while the other is blank. They were found on the coast of south Australia.

I have spent quite some time online but had no information. I was wondering the manufacturer and the name of the bullet.

Cheers Hamish.

I did not notice your previous input but could you please give the collectors an idea of dimensions.
We need the rim , base and mouth diameters even if fired and a case length to help ID.
Micrometer dimensions not from a ruler. I doubt I can help you . Good luck.

At first glance they look like Flobert cases, or could be BB or CB cap, which are rimfires which have no powder and use the fulminate for shooting. As Ron says, accurate case measurements would be very helpful.

I had one of my dads mates look at them, who believes they are 6mm floberts.

When the cases are measured the mouth measures just at 6.5mm, but that could also be due to erosion, or the time they have sat in the ground effecting them.

So I believe that could be the case. (As I have searched online and most dimensions line up perfectly)

However I am still unsure of the manufacturer. Like in the previous pictures you can see the headstamp is proud and it reads “SI” or “SL” (or maybe I’m reading upside down and it’s “IS”)

Any idea on the manufacturer?
Cheers Hamish.

Could it be a poorly stamped or worn SB for Sellier & Bellot??

I doubt it, I have three cases although weathered and eroded I can make out an S on two of them, I’m very sure it is an I for the second letter.

However I could be wrong as on both casings (with headstamps) the second letter has the strike mark

Regards hamish