The N.R.A. does have a strategic plan to defeat ISIS, and hope to have it implemented if they can gain the approval of the Joint Chiefs. It involves waging a war of attrition against the terrorists.
Because the main problem is that ISIS fighters blend into the population, the N.R.A.'s plan is to flush them out of hiding and eliminating them one by one. By making weaponry so easily available, they calculate that mass shootings become so enticing, ISIS fighters cannot resist the lure. Once out of hiding and shooting, they become targets, themselves, and are picked off in the ensuing firefight.
A little ingenuity can protect our Constitutional rights.