WASHINGTON — Rep. Denny Rehberg, R-Mont., working with the National Rifle Association, helped ensure this week that a proposed federal regulation opposed by gun buyers and vendors will be rewritten to address their concerns.

The Occupational Safety and Health Administration is updating its safety regulations on the handling and transportation of explosives. The agency’s proposed rule was written so broadly that it would have placed impractical restrictions on and likely forced the closure of many gun stores, Rehberg said.

Rehberg threatened to introduce an amendment to an appropriations bill on the House floor that would have prevented federal funds from being used to enforce the regulation. In response, an OSHA official wrote Rehberg that the agency never meant the rule to be interpreted that way and that it would be revised.

The agency will repropose the rule at a later date in order to clarify its intent, the Labor Department announced.

The proposed rule would have defined ‘‘explosives’’ to include black powder, small arms ammunition, small arms ammunition primers, and smokeless propellant and treated those items the same as the most volatile high explosives, Rehberg said.

A workplace with even a handful of small arms cartridges would have been considered a ‘‘facility containing explosives’’ and therefore subject to many impractical restrictions, he said.

In response, Kristine Iverson, a Labor Department assistant secretary said the rulemaking would be clarified.

‘‘It was never the intention of OSHA to block the sale, transportation, or storage of small arms ammunition, and OSHA is taking prompt action to revise this (proposed rule) to clarify the purpose of the regulation,’’ she wrote.

Iverson wrote that OSHA undertook the rulemaking because the existing explosives standard has not been changed in 35 years. The regulation needs to reflect new technologies and bring OSHA into agreement with other federal agencies that regulate explosives, she wrote.

‘‘It’s critical we ensure federal regulations are as up-to-date as possible to keep Montana’s work force safe,’’ Rehberg said in a statement. ‘‘However, it’s equally important we don’t burden local small businesses with costly regulations in the process. The OSHA rule would have required many gun vendors to follow expensive procedures which would have in turn driven them out of business.’’

Rep. Doug Lamborn, R-Colo., also gathered signatures from 25 House colleagues on a letter opposing the proposed rule.