Mr.Thilo Weissflog wrote a letter to the editor of the New York Times which suggests that the primary difference between the National Rifle Association of the 1930s and today is that, according to him, it has transformed from an organization advocating for responsible gun owners to one advocating for the gun industry. "Why else would its officials oppose the reasonable regulation of potentially deadly weapons?" he writes.
Having lived through the transformation of the NRA into what it is today, and knowing someone that worked on a state level to force the NRA to re-evaluate its position, I can say with a high level of confidence that Mr. Weissflog has it completely backwards. While there is little information I can find on the motive for the NRA's support of the National Firearms Act in the 1930s, by the time the 1968 Act rolled around, the NRA clearly was on the side of the American gun companies and dealers in supporting the Act because it cut off sales of firearms through the mail (to the benefit of the gun dealers) and protected the manufacturers from the flood of military surplus rifles that had been flowing into the United States. It was a grassroots backlash against the NRA's actions in regard to the 1968 Act that began to turn the tide; a backlash that grew only stronger with the NRA's support of the 1986 "Firearms Owners Protection Act" which outlawed the manufacture of new automatic weapons for civilian sale, and, as I witnessed, the NRA's tepid support (if even that) for "shall-issue" concealed carry laws in the late 1980's and early 1990's. By that point, many gun owners had developed a strong dislike, or even hatred, of the NRA. But the strong reactions against politicians that supported the 1994 assault weapon ban and the boycott against Smith & Wesson for bowing to the demands of the anti-gun hordes finally put some back-bone into the NRA.
It is a fear of a backlash from responsible gun owners that currently keeps the NRA in line.