[dsdmmat]

I did find a few things in the law.

Here is the most important part I found.
Laws of New York

§ 270.00 Unlawfully dealing with fireworks and dangerous fireworks. 1. Definition of "fireworks" and "dangerous fireworks". The term "fireworks," as used in this section, is defined and declared to be and to include any blank cartridge, blank cartridge pistol, or toy cannon in which explosives are used,................
3. The provisions of this section shall not apply to articles of the kind and nature herein mentioned.........
the sale or use of blank cartridges for a show or theatre, or for signal purposes in athletic sports, or for dog trials or dog training,

I also found the following Laws of New York

§ 265.05 Unlawful possession of weapons by persons under sixteen. It shall be unlawful for any person under the age of sixteen to possess any air-gun, spring-gun or other instrument or weapon in which the propelling force is a spring or air, or any gun or any instrument or weapon in or upon which any loaded or blank cartridges may be used, or any loaded or blank cartridges or ammunition therefor, or any dangerous knife; provided that the possession of rifle or shotgun or ammunition therefor by the holder of a hunting license or permit issued pursuant to article eleven of the environmental conservation law and used in accordance with said law shall not be governed by this section. A person who violates the provisions of this section shall be adjudged a juvenile delinquent.
This link talks about permits for display of fireworks. Laws of New York

It appears to me from my limited research you basically need a permit in order to legally use blanks. I hope the above helps more then it confuses.

ise the blanks to start a race every .4 seconds? lol