Revenue Ruling 58-586
Headnote
Where a person installs a telescopic sight on a complete new or used firearm, or cleans and blues a complete used firearm and replaces its sight and stock, his sales of such firearms are not subject to the manufacturers excise tax on firearms imposed by section 4181 of the Internal Revenue Code of 1954. However, where a person installs a sight and stock on a new or used barrel and action, which he owns or has sold to his customer, he is considered to have furnished material and manufactured a taxable firearm, the sale of which is subject to the tax.

