In a prepared response, MSHA said its investigators are "still reviewing evidence to determine the total number of bits with excessive wear."
"Water sprays were not working behind each of the bits on the tail-drum as required, because some of the sprays had been totally removed and the required pressure on each spray could not be maintained," MSHA said. "That being said, it takes only one bit without proper spray to allow an ignition to occur."
Massey also repeated its argument that a crack in the mine floor allowed a huge amount of methane to flood the mine, and that it was methane -- and not coal dust -- that fueled the powerful explosion.
But MSHA officials and McAteer have said physical examinations of the mine found no evidence of such a large methane blast, especially in the area of the floor crack.
MSHA has said that it found widespread violations throughout the mine of requirements that mine operators spread crushed limestone, or "rock dust," to keep coal dust from igniting. Massey on Friday repeated its believe that the MSHA sampling would be thrown out in court, as similar sampling was following a 2001 explosion that killed 13 miners in Alabama.
But McAteer and MSHA pointed out that conditions in the Alabama mine were much different than at Upper Big Branch, and played a major role in MSHA losing that legal case.
"The numerous differences at UBB include: different coal seam, no roof fall before, one explosion rather than two, not much rib sloughage, and only a small area of the mine was flooded," MSHA said in its statement.
At least one family member expressed frustration at the conflicting reports following Massey's meeting.
"They're really just contradicting each other," Clay Mullins, whose brother Rex died in the explosion, told The Associated Press.
Massey "put on a good show and had a lot of information to discuss," Mullins said, "... But I would have to lean toward MSHA. I think it's more an accumulation of dust."
Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.