Lock and load, mortgage shoppers, because years from now, even decades, you’ll look back on these rates as the good old days.

The U.S. fixed-rate mortgage market has not only settled at an historic bottom, it seems intent on digging even deeper.

Here are the numbers, as measured by the BankingMyWay Weekly Mortgage Rate Tracker. Thirty-year mortgage rates dipped below 5%, going to 4.97% from 5.04%, while 15-year fixed-rate mortgages are scraping the bottom at 4.46%, down from 4.5%.

Adjustable-rate mortgages aren’t as uniform, with one-year ARMs plummeting to 4.21% from 4.92%, while three-year mortgages took an opposite tack, rising to 4.42% from 4.41%. Five-year ARMs also rose to 4.33% from 4.23%. It’s been a nice ride as of late for adjustable-rate mortgage holders, with short-term rates especially knocking down mortgage rates and, in the process, monthly mortgage payments for ARM holders. That’s the one mortgage demographic that won’t appreciate the numbers we’re seeing this week.

Other than that, what’s going on with diving mortgage rates? It’s no mystery. While rates remain in what Wall Street mortgage traders refer to as a "contained range," the steady drift downward portends no confidence at all in an economic recovery. The trigger this week — and there always seems to be at least one weekly trigger — was last week’s housing start number.

According to the U.S. Commerce Department, via The Washington Post, housing starts "unexpectedly" fell back in October, "calling into question the strength of housing recovery." Housing starts fell by 10.6%in October, after a revised 1.9% gain the month before.

No doubt, not too many U.S. consumers view bad economic news as "unexpected." But nevertheless, the impact from the housing numbers was immediate. Look at the stock prices of major U.S. homebuilders— within 24 hours of the housing starts report:

• DR Horton (Stock Quote: DHI)  down $1.88 or 15.3%, to $10.37.
• Hovnanian (Stock Quote: HOV)  off 2 cents or .5%, to $4.06.
• Lennar (Stock Quote: LEN) off 50 cents or 3.5%, to $13.67.
• Pulte (Stock Quote: PHM) down 36 cents or 3.7%, to $9.46.

The takeaway here is an obvious one. If you’re looking for a new home, rates really can’t get much lower than they are right now. Plus, you’re still in the mix for the recently-extended home tax credit. As they say in the armed forces, it’s time to lock and load.

Take better aim by checking out BankingMyWay’s Mortgage Rate Search.

—For more ways to save, spend, invest and borrow, visit MainStreet.com.