More people are consigning more and more militaria firearms to auctions, according to Manion's International Auction House, based in Kansas City, US.
Manion's - a renowned seller of militaria, medals and other war related memorabilia - currently holds hundreds of firearms items available on the private market.
The auctioneer holds a Federal Firearms License, allowing it to buy and sell firearms.
"For whatever reason, [collectible firearms] are on the rise," said Manion's firearms specialist Patrick McWilliams, quoted on the News-Antique website.
"We're seeing more and more variety. Everything from $100 shotguns to World War Two German weapons worth several thousand dollars."
"We're listing between 10 and 20 different pieces a week - sometimes more," said McWilliams.
"We recently received a very rare Canadian Ross rifle, rejected as unsuitable for the trenches of France during WWI and sold to the US Army for use as a drill rifle.
"We also recently sold a one-of-a-kind Walther PP, presented by WWII German Reichsfuhrer Heinrich Himmler to a high ranking SS officer," he said.
According to Manion's, collectors are better off selling their weapons through a reputed dealer than trying to do it individually.
"Even with our commission, consignors generally receive much more revenue than they would through a local dealer or during a gun show," said McWilliams.