Last quarter, Rule Breakers pick TASER International (NASDAQ:TASER) turned a corner financially. Now, with Q4 and fiscal 2006 in the rearview mirror, it increasingly appears that the stun gun maker is around the bend.

Fourth-quarter sales were up 53%, while full-year sales were up 42%. Profits didn't show the exact same trajectory, thanks to a one-time $17.7 million payment to settle a class-action lawsuit. Discounting the settlement would have resulted in $13.6 million in 2006 profit -- a 12-times-over improvement from the year prior.

That said, I'm somewhat concerned by receivables growth. Accounts billed but not yet paid were up more than 85% in Q4, easily outpacing sales growth. That could be a cause for concern if TASER is extending extremely generous credit terms to its customers.

Chief Financial Officer Dan Behrendt told me in an interview yesterday that's not the case. Instead, he said that most of TASER's sales were closed at the end of the quarter. He also said that TASER is doing more business with state and local governments, which tend to pay at a slower pace than commercial customers.

That makes sense, which is why I'm willing to give TASER the benefit of the doubt for now. Still, we Fools should take note of receivables growth. It's getting out of hand:

Metric

Q4

Q3

Q2

Q1

Sales growth

53.0%

56.8%

22.9%

36.2%

A/R growth

85.7%

42.2%

19.6%

(63.4%)

Source: TASER press releases

And it's more troubling when inventory on hand declines in the face of higher sales, as was the case in Q4 and Q3. Oh, and Q1, too. Why is that a problem? Growing firms tend to stockpile raw materials to meet demand.

Behrendt, however, claims that TASER doesn't need the same stockpile that it once did. Like Dell (NASDAQ:DELL), the stun gun maker has apparently moved to a just-in-time production system that closely matches orders with needed inventory.

If that's true, then TASER may really be around the bend, with a wide-open road of returns ahead. Just be sure to watch those receivables if you take the wheel. They could prove to be the oil slick that sends your portfolio crashing into the wall.

A stunning array of related Foolishness awaits:

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Fool contributor Tim Beyers, who is ranked 1,704 out of more than 23,200 in our Motley Fool CAPS didn't own shares in any of the companies mentioned in this article at the time of publication. All of his portfolio holdings can be found at Tim's Fool profile. His thoughts on growth stocks, Foolishness, and investing in general may be found in his blog. Dell is an Inside Value and Stock Advisor pick. The Motley Fool's disclosure policy is a shock to Wall Street's system.