NATEC polymer ammo, buyer beware, maybe?
The stuff is made by a company called Natec. Its called PCA-spectrum. They have several different types all with different collored body. The red body is tracer. It is going for dirt cheap prices in the US.
I saw some of this and did a search on it. ARF has a review on it and it isnt good. Many complained of neck splitting and/or separations, as well as the small brass base being ripped off of the base of the body and being lodged in the locking lugs. Most said to save it for bolt action rifles and not bother with AR's or other semis.