OK, maybe it’s not as jaw-dropping as crashing the 5% or the 4% barrier. But Freddie Mac says 30-year mortgage rates have fallen below 3.8% for the first time to average 3.79%, down from a then-record 3.83% a week ago.

The 15-year fixed loan also hit another new low, falling from 3.05% last week to 3.04% this week in Freddie’s latest survey, released Thursday morning.

The start rates on adjustable mortgages rose slightly in the survey, which asks lenders what rates they are quoting to rock-solid borrowers with 20% down payments or equivalent equity in their homes if they are refinancing.

The borrowers would have paid 0.7% of the loan amount on average in upfront fees and discount points to obtain the fixed-rate loans, and slightly less for adjustable-rate loans.

The low rates have been a gift to people refinancing their home loans, a market also driven recently by a revised government program to help people refinance underwater loans.

A Mortgage Bankers Assn. report this week recorded a double-digit jump in applications for replacement mortgages, which now make up three-quarters of all home loan requests.