The "headway" so far is a slow process and mostly dependant on the courts, not presidents. The BO administration and the demoncratic party have simply either not allowed legislation to be introduced or the potential legislation never made it out of committee. Nothing was introduced by Republicans during the Bush Administration either. The National Parks gun issue started during the Bush Admin.
If the US EPA greatly oversteps from a practical perspective, businesses will simply stop complying with anything until they are caught. It is a tenuous relationship between business interests, believed people interests, and the interests of the EPA. The EPA claims they have science behind them. In reality, environmental requirements and enforcement should seek at middle ground allowing some gain relative to the environment versus cost which is spread out over a long period of time and there is clear cut science to back them relative to risk to human health and the environment. It is much like the progressive movement in general who seeks the slow socialization of the USA. BO has said that salvation is a collective issue not an individual issue. That clearly illustrates his progressive nature and likely his views on gun ownership. I don't think it is clear yet that outlawing lead from shotshells, single bullets, or fishing lures or sinkers would clearly represent a significant gain to the environment on a national basis whether it be in lakes and streams or soils. There will always be organizations pushing their individual causes whether it be gun legislation, improving duck or fish habitat, replacing wetlands, new septic tank or sewage requirements in rural areas, whale harvesting, etc.