The Curio Shop, in George Street, attracts interest from all over the world and has even caught the eye of famous musicians.
Packed from floor to ceiling with thousands of historical gems, each week it is visited by scores of antique hunters and curious shoppers looking for something unusual to fill a space in their homes.
The store is increasingly attracting a younger audience with an eye for vintage, chic items.
From old fashioned phones and furniture to trinkets and money boxes, owner Spencer Evans has trawled through homes, searched market stalls and bought treasures from his own customers.
He came across the gun sight just last week and believes it is from an English firearm, but he is hoping to find out more as he researches his latest additions.
"I was born with an interest in antiques and all things old," the father-of-two said.
"I've always had a fascination for old things, social history and the way we used to live. Life has changed so much.
"I look for quirky things and those which will make an impact."
The only item not up for sale in the shop is a long, thin 1913 American hoover, which works by pumping the handle up and down by hand and was found in an outhouse in Walsall.
Mr Evans, aged 44, of Highgate, Walsall, said: "It's a novelty item. I've had it in my collection for the last 25 years.
"I've just sold a 1950s Hotpoint washing machine to someone in London which still works. The moment I saw it, I loved it. It has a classic design. I bought the solid brass gun sight last week and I just got a 1980s Russian sailor hat from the Baltic Fleet from someone on a market.
"There are Roman brooches in the shop which are 2,000 years old. Some people found them with metal detectors in the West Midlands. They are only tiny but would have been worn on tunics. I've met all kinds of people with lots of different tastes. If I don't have something in, I will try and find it.
"I once found a Victorian upright piano and delivered it to a customer in Paris."
Mr Evans said he also once sold a trumpet to Roy Wood from Birmingham-based band Wizzard, and on another occasion a gyrating Elvis radio was bought by Alain Whyte, Morrissey's guitarist.
Furniture from the 1960s and 1970s is now being sought by visitors to the store and there has been a notable rise in teenage and younger customers in recent years. "They love the shabby chic and vintage look," said Mr Evans, who has also been selling from market stalls in Walsall for the past five years.
Among the other antiques in the store are a 1949 Boys Book of Heroes annual, 1930s pixie statue and 1970s Donald Duck money box. Mr Evans said he was called up on a weekly basis to take part in house clearances and was hoping to do more in the future, employing an additional member of staff to help. The business was opened in Freer Street by John Owen, who was originally from Wednesbury, on April 3, 1969.
Mr Evans came to work for the business in 1992 – three years before Mr Owen died, aged 58. The shop moved to its smaller base in George Street in 2009 because the former site was ruled structurally dangerous by engineers. The Grade II listed building was ordered to close by Walsall Council in December 2008.