Hours after the National Rifle Association was hit by a lawsuit from New York’s attorney general on Thursday seeking to have the gun lobby dissolved over allegations that millions of dollars were diverted to pay for the lavish lifestyles of its leaders, the NRA’s CEO, Wayne LaPierre, hit back.

In typically pugnacious fashion, LaPierre issued his own counter-suit against the attorney general, Letitia James. In a rallying cry to NRA members, he accused her of “weaponizing” her regulatory powers and “politicizing” her office in an “affront to democracy and freedom”.

If LaPierre, 70, was hoping to spark a new culture war between the hyper-conservative group he runs and one of New York’s top Democrats, it is not clear the strategy will work this time. For almost 30 years LaPierre has used the same aggressive tactic to build up the NRA into the world’s largest and most feared gun advocacy group, with 5 million members, steering it in an ever more partisan direction that has culminated with its enthusiastic support for Donald Trump.

But misgivings about the inner workings of the NRA are not confined to prosecutors in the progressive outpost of New York. Inside the organization itself, there is a groundswell of discontent relating to the alleged misuse of millions of dollars from the association and its charitable arm, the NRA Foundation.

Speaking to the Guardian from Nashville, Tennessee, one of the NRA’s top donors was unrestrained in his criticism of LaPierre and the 76 members of the NRA’s board who he accused of collectively turning a blind eye to alleged financial impropriety.

“It makes me feel sad and depressed,” Dave Dell’Aquila said shortly after the New York lawsuit had been lodged. “And angry. Extremely angry. I’m angry that a 152-year-old historic institution has been taken down under Wayne LaPierre and his management team, while the board of directors let this happen.”

Were LaPierre tempted to try to squeeze Dell’Aquila into the same gun-hating, freedom-loathing pigeonhole in which he crams Letitia James, he would have a tough job. It’s not just that the former tech company boss is a lifetime member of the NRA and has given more than $100,000 to forward its core mission.

It’s that Dell’Aquila has had guns and hunting in his blood, ever since he first caught the firearms bug aged 10 growing up in Pittsburgh, Pennsylvania.

There’s a clue to which side of the second amendment right to bear arms debate he stands right there in his front room. It is dominated by a stuffed 400lb black bear he shot a few years ago in Canada.

He’s currently expecting a shipment of 15 animal trophies from a recent hunting trip in Africa, including heads of sable and eland antelopes. “I’m a conservative honest supporter of the second amendment. I passionately believe you are entitled to firearms to protect yourself and to keep dictatorships and monarchies out,” he said.

And so the website Dell’Aquila created, retirelapierre.com, cannot easily be cast as the work of a socialist ideologue out to get your guns – a favorite talking point of LaPierre’s.

Equally, the class-action lawsuit Dell’Aquila initiated in a federal court in Tennessee in August 2019 carries the weight of an insider.

The suit, brought against LaPierre personally as well as the NRA and its foundation, is strikingly similar to New York’s action. It recalls how Dell’Aquila donated $100,000 to the organization thinking it would go towards promoting shooting and hunting, gun safety, wildlife conservation and the right to gun ownership in the US.

It then recounts how he discovered that far from going towards these core objectives, his money was allegedly contributing towards the luxury habits of LaPierre and other top NRA executives. Through the 2018 investigation conducted by the NRA’s then president, Oliver North of Irangate fame, Dell’Aquila learned of allegations that over several years “LaPierre had received hundreds of thousands of dollars in clothing, private jet travel and other benefits”.

In particular, Dell’Aquila’s suit alleges, some $243,644 was spent on “luxury travel for LaPierre to the Bahamas; Palm Beach; Los Angeles; Reno, Nevada; Budapest, Hungary; and Italy”. The court document further cites spending of $274,695 at a Beverly Hills clothing store on suits for LaPierre – none of which was declared under IRS tax filings.

A similar theme is taken up by the New York suit. It accuses LaPierre and three members of his top team of creating a “culture of self-dealing, mismanagement and negligent oversight at the NRA that was illegal, oppressive and fraudulent”.

Such financial impropriety contributed to total losses to the NRA of an astonishing $64m, the prosecutors allege. Hundreds of thousands of dollars of charitable money went on private jet trips for LaPierre and his family, at least eight trips to the Bahamas over three years costing more than $500,000, and use of a 107ft yacht owned by an NRA vendor.

The CEO also allegedly went on an African safari, all expenses paid, and spent almost $4m on luxury limousines in the past two years alone. The suit says he negotiated without board approval a post-employment contract in which the NRA would pay him $1m a year for the rest of his life after he retires or steps down – a package worth $17m.

In its counter-suit, the NRA claims that the New York attorney general was trying “to silence the NRA’s advocacy and neutralize it as an opposing political force”. In his letter to NRA members following release of the legal action, LaPierre said: “The NRA is well governed, financially solvent, and committed to good governance.”

Responding to Dell’Aquila’s lawsuit, the NRA has argued that as a member of the group he has no standing to sue and has asked a federal judge to dismiss the case. A ruling on the motion could come any day.

But for now there’s no stopping Dell’Aquila. He is apoplectic above all about the post-employment contract, contrasting its largesse to the meagre incomes of many of the NRA’s members.

“I mean, how does Wayne have a $17m contract after he leaves the NRA? On top of the close to $2m he earns a year with stock and everything like that? Two million dollars to run a non-profit? You gotta be kidding me.”

Dell’Aquila began his investigation into NRA dealings two years ago. It started simply enough, with him asking himself where his $100,000 donation was going yet finding it hard to get satisfactory answers.

Then he noticed how decision-making within the NRA was tightly controlled around LaPierre and his top team. “I started to see cliques. The NRA’s inner circle is very cliquish. That’s one thing if you are doing a good job, but then I started to see money unaccounted for, wasteful spending.”

Dell’Aquila began to see LaPierre as a king figure. “He thinks he is above the law. He’s been in charge for 30 years. Presidents and their administrations come and go, but he stays. He’s not accountable and he gets away with it – I just think it’s gone to his head.”

Dell’Aquila spent an intense year working around the clock, putting questions to the chief executive and the board but rarely getting answers back. Employees, he said, began privately coming to him with inside information.

If he has criticisms of LaPierre, he reserves his biggest complaints for the board of directors who have remained overwhelmingly loyal to the NRA leadership despite mounting evidence of alleged malpractice. “Wayne couldn’t have done all this stuff – the trips to the Bahamas, the special security, the suits, the private jets – without the board. They have financial oversight, they can demand documents. They could convene a vote and get Wayne out, so why don’t they?”

Over the past 20 years, the NRA has created a mythology around itself that portrays it as an unassailable, united, unstoppable force at the heart of conservative America. But as the edifice begins to crumble, voices like that of Dell’Aquila – coming from the inside – are finally beginning to be heard.

For his part, he hopes that his class action will prevail and that on the back of it the $64m will be repaid, the current board will be replaced, and that a new NRA will emerge from the ashes. He believes one other thing must happen – LaPierre must be forced out.

“I’m not pro-Wayne, I’m not negative-Wayne. I’m objective Wayne,” he said. “For the good of the NRA – Wayne must go.”