Uncertainty continues to be the constant at the Mine Safety and Health Administration (MSHA), where, in the past year, the budget was cut, coal mining fatalities climbed and the budget was restored.

Now, congressional action and reorganization have resulted in a cut of more than 300 authorized jobs. No one knows how many real people will lose work, but many of those whose positions have been abolished are eligible to "bump" MSHA employes with less seniority. The bumping process has hurt morale and has reduced MSHA's effectiveness in the field, according to critics.

So far this year there have been 48 coal mining fatalities nationwide, compared with 39 for the same period last year. In 1981, the worst year for fatalities since 1975, 153 miners were killed.

Coal mining is the primary target of MSHA's enforcement efforts, but the agency also has statutory responsibility for safety in sand, gravel and stone operations. However, in a continuing resolution last December, Congress prohibited spending for that purpose. As a result, 220 sand, stone and gravel inspectors were furloughed indefinitely. Many of them them bumped less senior coal mine inspectors.

In March, with the appropriation bill from MSHA's parent Labor Department among those still unresolved on Capitol Hill, Congress adopted another continuing resolution to finance MSHA for the rest of the fiscal year, but continued to prohibit sand, gravel and stone inspections.

So now, 260 positions in sand, gravel and stone inspection have been abolished, and the bumping process has started anew. "We have morale problems among inspectors already, and this will lead to more," said John Jarvis, legislative manager for the United Mine Workers here.

Theoretically, Labor's Occupational Safety and Health Administration (OSHA) should pick up responsibility for sand and gravel inspections. However, OSHA does not inspect firms with fewer than 10 employes unless there is a complaint or a reported accident, and thousands of sand and gravel operators have fewer than 10 employes.

So far this year 13 deaths have been reported in sand and gravel pits, compared with 20 at the same time a year ago, but officials say they believe some fatalities may have gone unreported because federal enforcenment is in limbo. "Congress and the Reagan administration are abdicating their responsibility," Jarvis said.

In addition to the sand and gravel issue, MSHA is eliminating separate education and training offices and reassigning those personnel to inspection offices.

MSHA personnel specializing in settling differences between mine operators and enforcers have been cut from 121 to 38 and reassigned to district offices. There has been no reduction in the number of coal mine inspectors, officials said.