For cutting, security systems, gunsights, sky writing, communications, accurate measurement,

A gun sight on a chainsaw is a mark across the top and side of the chainsaw case. This mark is made perpendicular to

the saw bar and on some saws is molded on the case. This can be characterized as the letter "T". The top of the T is your mark with the vertical line of the T being the bar of the saw.

Ghost rings are meant to be used in close quarters. If you place the top of the post in the center of the ring, then place the post over your target, you will hit your target. The difference between a peep hole sight and a ghost ring is the absence of material surrounding the rear aperture.

Do not recall them as a manufacturer- although just about every company made something for the military. IIRC, Kodak was busy making cameras, film, telescopes, and gunsights/ bombsights. Link below to WWII Kodak ads.

The Winchester Model 68 bolt action single shot .22 was made from 1934-46. It did not have a rear sight mounted on the barrel, but had a receiver mounted Winchester No. 96A peep sight (books at $20-40). As options, Winchester offered the Lyman No. 55W or 57ES Receiver Sights ($25-75). The hunt for old gunsights can pretty interesting. Lyman is still in business, and may be of some help. Good luck. By the way, the rifle (with sights) books from $275 at 100% to $50 at 60% condition.