CHICAGO (MarketWatch) — Sturm Ruger & Co.’s announcement that it would stop taking orders until it clears an enormous backlog serves as the latest sign of the boom times for the U.S. firearms business.

Late Wednesday, Sturm Ruger RGR, -1.49% said that in the first quarter, it had received orders for more than 1 million units. And despite “efforts to increase production rates, the incoming order rate exceeds our capacity to rapidly fulfill these orders,” Sturm Ruger said.

The company, which makes a wide variety of rifles, pistols and revolvers, said that it expects to “resume the normal acceptance of orders by the end of May.”

That sent Sturm Ruger’s shares up about 13% in trading Thursday. Rival Smith & Wesson Holding Corp. SWHC also got a bump, with its shares gaining about 11%.

For its part, Smith & Wesson forecast sales of $395 million to $400 million for all of fiscal 2012 when it released third-quarter results this month, up from an already-increased December estimate of $385 million to $395 million.

“We continued to work on expanding our firearm manufacturing capacity to meet increased demand, an objective we plan to continue in the coming months as we address our robust backlog,” Smith & Wesson said.

Its firearms backlog was, at the end of the quarter, $198.5 million — more than double the figure of a year earlier.

Recession-proof

As an industry, firearms have barely felt the impact of the downturn. In fact, the opposite has been true.

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Starting in 2008, it has grown almost constantly, fueled by economic uncertainty and never-realized worries that President Barack Obama and the then-Democratic controlled Congress would seek to rein in gun rights.

Adding to the jump in demand were several Supreme Court decisions affirming that the right to bear arms is indeed an individual, one as well as the reappearance a year ago of firearms in hundreds of Wal-Mart Stores Inc. WMT, -0.08% outlets.

In its crunching of National Instant Criminal Background Check System data, the National Shooting Sports Foundation said that 920,840 checks were made in January alone, a gain of 17.3% over the same month in 2011. That made it the 20th consecutive month of increases.

And, while the number of background checks is a good barometer of sales, it doesn’t tell the whole story, as some of them may have been performed for purchases of multiple firearms.

In addition, some private transfers and gun-show sales are exempt from the background-check requirements, so the actual number of guns sold is likely higher.

Earlier this year, the NSSF said at its annual trade show that “many indicators, including a record-setting 2011, show the firearms industry continues to thrive in a down economy and that the potential exists for another strong sales year in 2012.”

Demand “has continued at a robust pace since late 2008,” it said, as “more and more Americans are choosing to exercise their Second Amendment rights.”

The Freedom Group is the largest maker of commercial firearms and ammunition in the U.S., with brands including Remington, Marlin and Bushmaster.

In a financial report late last year, the company said that “in 2011, demand for modern sporting rifles and handguns has continued an upward trend in the industry.”

However, “long gun sales are focused on low to medium price points” and “consumers are currently focused on products with lower average selling prices.”