Universal’s debut chiller “Mama” saw a slight three-day bump vs. earlier estimates, at $28.5 million, but the studio released four-day projections that were a tad more conservative. Estimates of $33 million would still easily make it the No. 1 film over the long Martin Luther King Jr. frame.While box office receipts generally fall 25%-30% on the holiday itself, horror films tend to drop more, a result of conflicting word of mouth. Universal estimated “Mama” to fall roughly 40% from Sunday; the film could actually do better given its strong teen turnout. In second place domestically, Sony’s “Zero Dark Thirty” also went down in four days, with $18.7 million, compared to the studio’s previously estimated $21.4 million take. The film still held exceptionally well, dropping only 35% from last weekend’s three-day frame. Stateside cume is just north of $57 million. The NFL playoff games on Sunday likely had a larger-than-expected effect on overall box office. Still, the power of both Jessica Chastain starrers helped boost domestic totals roughly 8% above this time last year, though the other wide openers, Fox’s “Broken City” and Lionsgate’s “The Last Stand,” each underperformed. “Broken City,” starring Russell Crowe and Mark Wahlberg, came away with an estimated $9.5 million in four days — $1 million less than estimated on Sunday — while Arnold Schwarzenegger’s “The Last Stand” is projected to earn $7.2 million through today vs. Lionsgate’s $7.4 million four-day estimate released Sunday. In limited release, Indomina’s coming-of-ager “LUV” averaged $2,222 from 45 locations in four days for a total of approximately $100,000 through Monday. Michael Apted’s latest docu installment in his continuing Brit series “56 Up” sold out locations at L.A.’s Landmark Nuart this weekend. Pic, which is also playing at four locations on the East Coast, grossed roughly $32,000 through Sunday, for a domestic cume of $91,501 in three weeks.