Remington 12g Modi-pac plastic loads

For you, shotgun shell lovers!! Have no idea if it is rare, it was in a box I dragged away from a show. I am sure it works well for shredding paper documents. The shells have high profile brass, usually reserved for strong loads, but the bottom label says not to use in autoloaders, implying weak load. The shells are solidly packed with white bb size plasic balls, the shells are semi-transparent. The bottom label implies that certain types of barrels may be damaged. Damaged by plastic pellets?

This is a riot loading for use by LE. M. Rea

The question of the Modi-Pac, law enforcement shells has been asked several times before on the forum. If you do a forum search, I believe your questions will be answered.
Regarding the warning statement on the box label about not using in Damasus or twist barrels… this is a more or less standard warning not to use a modern smokeless powder load in an older gun that was built to use black powder only. It has nothing to do with what kind of pellest the shell is loaded with.

I have always wondered about these. Mine has a Remington/Peters HS with a red cardboard TW. Thanks for the info.