Your sample is of very bad quality to be sure, but it looks like a common condensed sans font e.g. Helvetica (Narrow)
Do you have any better samples?

Unfortunately not, because my iPhone can´t make any macro shots. Can only make pics from a longer distance without getting blurry.

tried another one. maybe it helps.

The quality & resolution of the picture is good enough.
What I was asking is a photo of another physical sample i.e. if you have the old stamp you could try to make a new sample by laying out the stamp carefully on a smooth white paper to show us as many details as possible.
If this is your only sample, then we can only make general assumptions and Helvetica Narrow still looks good enough for me.
Take also into account that if the stamp is τοο old [i.e. 10, 15, 20 years] the technology used to create it could vary and the fonts used (which were proprietary at some point back in time) may not correspond to any modern digital font.

Thanks for your help.

I guess the stamp should be 6 or 7 years old.
It is currently in a shop that tries to figure out to copy it, but can´t find out which font is used.
That´s why I was hoping to get help here.

We are using it as security stamp for our products and our staff is used to the look of the stamp when checking the products so that we want the exact same font.

I tried Helvetica Narrow, but it seem that it is not the font.