Even a water resources development bill can’t escape the fissures on the Second Amendment in the Senate.

A clear majority of senators voted for an amendment from Sen. Tom Coburn, R-Okla., expanding legal access to guns at federally controlled water project sites before getting into much of the debate on the underlying water resources authorization.

The 56 “yes” votes were short of the 60 that would have been required for adoption under a unanimous consent agreement, as Democrats would have no doubt filibustered the amendment if necessary. Illinois GOP Sen. Mark S. Kirk voted against Coburn’s amendment, while a dozen Democrats voted in favor of it, including a number of senators facing voters in 2014.

Wednesday’s vote is another sign of the balancing act that Democratic leaders face in moving gun legislation such as the proposals to expand background checks or to curb ownership of high-capacity gun magazines. In theory, there may be no connection between allowing legal gun owners to have their weapons at Army Corps projects and the background check system, but the debate highlighted the Senate’s reluctance to restrict firearms access in general.

Coburn offered his measure as the first Republican amendment to a pending water resources bill. It would allow legal firearms owners to have their weapons at Army Corps of Engineers water projects. Coburn said that would make Army Corps land subject to the same standard applied to National Park Service land under an amendment adopted by the Senate in 2009, with 69 votes.

Coburn highlighted that and other efforts to expand the ability of those with valid weapons permits to carry their firearms.

“When you accidentally walked onto U.S. forest land you are actually violating federal law even though you might not have known you were on state land versus federal land,” Coburn said. “And I would note since that time, the amount of crime in our national parks has declined. So since then, we now have throughout the country the same approach that we have in national parks, on Bureau of Land Management areas, the Forest Service, the National Park Service and the national wildlife refuge.”

Coburn’s efforts to expand legal firearms access extend over several years. In 2010, CQ Roll Call reported on the strategy, with one top Republican aide saying at the time that the Oklahoma Republican planned a “Pattonesque approach to amendments.”

Similar firearms-related votes have taken place many times before, including regarding transporting guns via Amtrak trains. Coburn also contributed to tripping up District of Columbia voting rights over an expansion of gun rights within the District that drew fierce opposition from local officials.

“After we passed those amendments, the Corps proactively stated that none of this applied to them,” he said Wednesday.

Sen. Barbara Boxer, D-Calif., sparred with Coburn on the floor, arguing that sites such as dams and reservoirs are different from national parks because they are critical infrastructure facilities that could be put at risk by guns.

“I believe this amendment would put our national security at risk by making the nation’s dams, reservoirs, hydroelectric power houses, navigation locks, major river systems, levees and other flood-risk-management features vulnerable to attacks,” Boxer said.

Though Boxer ultimately prevailed, the vote put guns back on the Senate’s front burner, three weeks after the chamber failed to adopt any amendments to tighten background checks and other gun laws.

Though the Senate has tried to move on, the background check debate shows no sign of fading soon. Vice President Joseph R. Biden Jr. and Texas GOP Sen. Ted Cruz have written opinion pieces for the Houston Chronicle on opposite ends of the debate in recent days. The National Rifle Association held its annual meeting this past weekend in Houston.

Biden wrote that his takeaway from the Senate votes on background checks was that there’s a real movement in the country in favor of expanded background checks.

“Today, those very senators are discovering that the political landscape really did change. They are learning that Newtown really did shock the conscience of the nation and that inaction will not be tolerated by Democrats, Republicans or independents,” he wrote.

But Cruz and other opponents of a broad expansion of background checks have kept up the argument that such measures could impede private firearms transfers.

“Even more ominously, the long-term objective of extending background checks to private citizens is the creation of a national gun registry, a federal government list of every firearm owned by every American,” Cruz wrote. “To be sure, the latest Senate legislation purports to prohibit a gun registry, but the Obama Justice Department has been explicit about its ultimate objective.”

Coburn did not offer a second firearms amendment Wednesday that would have required annual reporting on firearms and ammunition purchases. Democrats suggested that amendment could have actually given fodder to their side of the underlying argument about tracking weapons.