Ronald, The warning is all about the ammunition and results of shooting the ammunition to get lead and other chemicals in the air. The ammunition firing warning is getting very common on many firearms.-------WARNING: This product can expose you to Lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to ********- P65Warnings.ca.gov.

upon further research the Mossberg ATI has a CA P65 cancer warning! most likely due to some material uses In the stock see****** The ATI Halo Heatshield is a free-float design with front/rear blocks and silicone pads, that provide no metal-to-metal contact with the barrel. A front dovetail rail attachment comes with two 2” rails for accessory mounting convenience. A shield-mounted post front sight provides clear sighting. The ATI Halo Side Saddle is mounted directly to the 500 shotgun’s tapped receiver. Three Add-A-Shell units are included, that mount to any of 9 possible positions. Each Add-A-Shell unit can be flipped 180° for user-preference of brass up/brass down orientation. A removable top rail provides for a variety of sight or accessory mounting options.

Made In United States of America
******WARNING: This product can expose you to Lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to ********- P65Warnings.ca.gov.

that's a new one on me but CA has some strange laws and nothing would supprise me

Ronald, this is the 1st I have heard this Sir. I'll see what I can find. Cheers!