Blank or Igniter

I hope someone can identify this unusual cartridge.
The rim is very thin. Brown lacquered wad. Looks USA military issue.
Headstamp is: F 1 3 4 3 5 - 5

Length is 33.4mm. Rim is 11.9mm. Base is 9.66mm. Mouth is 9.54. Rim is 0.86 thick.

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Hi Ron,

It’s an example of a US 20 grain primer type as used with 37 mm and 1.457 subcaliber caliber cases. This is the standard size used since the 1890’s in 1 Pdr cases and as late as WW2 in 37 mm AT and Aircraft Gun cases (WCC 42 headstamp, for example). The only thing that has changed along the years is the construction and cap size used, but outside dimensions remain the same.

Your example is WW1 contract that is found in Frankford Arsenal 1.457 subcaliber cases.

Excellent find!

Regards,

Fede

Thanks Fede. I did not guess it was a primer.
I will check my 37mm but not sure I have one using this primer.