I don't think that's accurate, but I understand why you say that.

The tax on suppressors (and automatic weapons) is often several hundred percent, because the legislature and regulatory agencies are not allowed (by the supreme court's opinions in the last few decades) to outright BAN them. The very high tax is pretty much the only way they have to restrict the sale of those items.

I've never heard a gun enthusiast say they shouldn't have to pay sales taxes. (Well, that's not true because there's some overlap between gun fanatics and libertarian tax radicals.)