Kel-Tec has discovered a potential issue with the Sub-2000 rifle. Although it only affects a limited number of firearms, all sub-2000 rifle owners are advised to stop use until they can determine whether their firearm is affected and/or repaired. Here is the full recall notice from Kel-Tec. 
Important SUB-2000 Safety Recall Notice
We have recently identified an issue with the heat treatment of certain steel tubes received from a third-party supplier from which the barrels for a limited number of Kel-Tec SUB-2000 rifles were manufactured. This could potentially cause the barrel to rupture when a cartridge is fired and could result in serious personal injury. The safety of our customers is our primary concern, so Kel-Tec has voluntarily initiated this recall because of the possibility of a barrel rupturing.
This recall only affects a portion of SUB-2000s that were manufactured in 2017.
To check if your firearm would need to be sent in for barrel replacement, please follow this link: SUB-2000 Recall
All costs associated with the recall of your firearm shall be covered by Kel-Tec.
So what exactly does Kel-Tech produce, if they “Don’t” actually manufacture anything…