Maybe, maybe not. Depends on how you define it. Let's look at the '86 grossly misnamed gun owner's protection act (i.e. full auto ban.) It passed the Senate 79:15. At the time the Senate was R:D 53:46 which means that if NO Democrats voted against it then 79-46 = 33 Republicans voted for it. 33/53 = 62.2% of Republicans voted for the semi-auto ban so statistically speaking Republicans are to be trusted with our gun rights less than half the time.
Republicans are, on average, more susceptible to pressure to do the right thing.
perhaps although I'd have to have pre and post calling/letter writing campaign pro/antigun stance of legislators to quantify this. The analysis would be a straight forward chi Square
Bottom line: you can't trust Republicans just because they have an R after their name.
The '86 full auto ban was only a small part of the Gun Owners' Protection Act.
The critical vote was a voice vote fraudulently done by the Democrats.
It was not even clear at the time, that the '86 law actually banned production of more full autos. It allows for production under the authority of the government.
Gun owners had been fighting for years for the reforms which were enacted. The activists were not willing to throw them all away because of the poison pill of the '86 full auto ban.
It is horribly bad law, I would say, blatantly unconstitutional.
But it is wrong to claim it was the major focus of the bill at the time.