Charges of illegally possessing or carrying a firearm have been less every year than in 2009. There were 1,963 such charges in 2009 and 1,216 last year.
National Park Service spokesman Mike Litterst said the service does not have information about rapes and murders readily available and did not provide it to Coburn's office.
Sen. Barbara Boxer, D-Calif., the author of the water projects bill that Coburn sought to amend, argued that Coburn's proposal didn't belong on the legislation.
“This is not a gun bill,” she said. “This is not a place to add these types of amendments … It isn't necessary; it isn't appropriate.”
Boxer also complained that Coburn's amendment would allow people to carry weapons at dams and locks and other infrastructure that could be vulnerable to terrorist acts. Coburn said a separate federal law prohibited carrying weapons at such critical structures and that his amendment would not affect that law.
The debate came less than a month after Senate leaders shelved a gun control bill. Coburn, who has been a fierce defender of Second Amendment rights, was heavily criticized in Oklahoma for voting to advance that bill past a procedural hurdle so it could be debated. Coburn later voted against a bipartisan proposal to expand background checks and others to ban certain weapons and ammunition clips.