No provision hereof shall prevent that private collections of antique firearms, which may not be used as weapons, be preserved and maintained and that their owners possess them as ornaments or as matters of curiosity, nor the collections of firearms kept as relics, but for the preservation of any weapon of those included in this section the prior inspection thereof and approval therefor by the Commissioner shall be necessary and he shall render such firearms useless, so that the same may not be used as such. The Commissioner shall issue a certificate of uselessness of all the weapons possessed under the provisions of this section, and the possession of any firearm not included in said certificate shall be subject to all the provisions hereof.