Grandmothers Cast Iron ID

Cooking for my late teen aged daughters today and they became interested in their great grandmothers cast iron skillet. Sent me to the internet to see what I could find out.

I believe the skillet to be a Lodge 7SK. Three notches in ring, what seems correct font.

But the letters HT appear at the top of the skillet (12 o'clock) above the 7 and the letter H is at the bottom (6 o'clock). Pictures I've seen do not ssem to have that.

Just trying to narrow down the age a little.

I believe I have added photos, any assistance is appreciated.

If there is no "Made In USA" inscribed on the bottom, this Lodge pan would have been produced sometime in the 1950s. The additional letters, being inscribed, would have to have existed on the pattern before the sand mold was created. As such, they are some kind of identifier, either for quality control, shift, production line, or some combination thereof.

No made in the USA. What is in the photos are the only marks. Sorry should have been clearer. Thanks for the reply. Had hoped it went back to my grandmothers mother...but probably not.