Does it fit in a byrna?

These are 50 Cal aluminum balls which fit for T4E TR 50, HDP 50, etc. If you're looking for 68 Caliber balls, please try this: https://www.amazon.com/gp/product/B0BZRKHBKD

How much does one ball weight in grams and also what is the actual diameter of one ball?

These are a hard plastic. They are .50 caliber which is 1/2 inch They are pretty light weight

Will they stop a person or put them down

That I imagine would all depend on the person and if any thickness of clothing or armor to be a factor but it would hurt, I would imagine, and change most people minds of possibly doing you harm

Color	Silver
Size	50. Cal
Material	Aluminum
Sport Type	Paintball
Batteries Included	No
Package Dimensions	13.31 x 8.51 x 3.1 cm; 2.8 g

Alien Play 100 Rounds Solid Aluminum 50 Cal Paintball Ammo Self Defense 2.8 Gram 0.50 Cal Powerful Projectile for t4e TR50/HDR 50

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