Can someone tell me . . . .

[JimF]

. . . .who made this elevation drum?

I just found another T105E1 rear sight with the elevation knob marked "ISS".

The "I" may be another poorly-struck letter . . . hard to tell.

Anyone know who "ISS" is/was?

Many thanks for any responses, --Jim

[CPC]

Maybe you are reading the stamp backwards and it is really SSH with the H partly missing which is very common. Trying to remember without looking it up but I believe that could be Sessions Clock Company. Spelling could be off.